Association between obsessive-compulsive disorder and the risk of schizophrenia using the Korean National Health Insurance Service-National Sample Cohort: a retrospective cohort study.

AIMS: Obsessive-compulsive disorder (OCD) and schizophrenia are often reported as co-morbid conditions. However, the evidence of an association between OCD and the risk of schizophrenia is limited. This study investigated the risk of schizophrenia in patients newly diagnosed with OCD using a nationally representative sample cohort in South Korea. METHODS: Data were obtained from the 2002-2013 Korean National Health Insurance Service-National Sample Cohort of the National Health Insurance Service. Using propensity score matching, 2509 patients with OCD and a control group of 7527 patients were included in the analysis. Chi-squared tests were used to investigate and compare the general characteristics of the study population. The risk of schizophrenia was analysed using the Cox proportional hazard model. RESULTS: The incidence rate was 45.79/10 000 person-year for patients with OCD and 4.19/10 000 person-year for patients without OCD. Patients with OCD had a higher risk of schizophrenia compared to the control group after adjusting for covariates (hazard ratio = 10.46, 95% confidence interval = 6.07-18.00). CONCLUSIONS: This study identified an association between the diagnosis of OCD and the risk of schizophrenia in a South Korean national representative cohort. Further research using a prospective design to clarify the causality of OCD in schizophrenia in a controlled environment should be conducted to validate these findings.

Association of exposure to secondhand smoke at home with early age at menarche in South Korea.

OBJECTIVES: The secular trend in age at menarche (AAM) has declined both worldwide and in Korea. Early AAM is associated with the risk of several diseases, reproductive capacity, and psychological problems. We aimed to investigate the relationship between secondhand smoke (SHS) exposure at home and early puberty onset using AAM in Korean adolescents. STUDY DESIGN: This is a retrospective cross-sectional study. METHODS: This study used data from the Korea Youth Risk Behavior Web-based Survey 2014-2015. We used the mean AAM (12.2 years) as a determinant of early AAM. After the exclusion of girls without menarche or who did not respond, the total population comprised 63,618 participants. We categorized AAM as 'early' and 'average or late.' Adolescents with SHS exposure were assigned to the 'never exposed,' 'light exposure,' and 'heavy exposure' groups. Multiple logistic regression analyses were performed. RESULTS: We observed a positive association, approximately 1.12 times, between early AAM and high SHS exposure (odds ratio [OR], 1.12; 95% confidence interval [CI], 1.05-1.19). Girls who started smoking before the age of 12 years (OR, 1.68; 95% CI, 1.41-1.99) showed a stronger association with early AAM than non-smokers. Active smoking showed a stronger association with early AAM. Never smokers with high SHS exposure at home were 1.13 times likelier to have an early AAM (OR, 1.13; 95% CI, 1.05-1.22) than those without SHS exposure. CONCLUSIONS: In addition to active smoking, SHS may also be a risk factor for early AAM. Education aimed at active and secondhand smoking prevention is needed to protect children against early AAM.

miRNA expression profile of mucoepidermoid carcinoma.

OBJECTIVES: MicroRNAs (miRNAs) are single-stranded RNAs that have been implicated in cancer initiation and progression and act as tumour suppressors or oncogenes. In this study, miRNA profiling was conducted on the most frequent malignancy of salivary glands, mucoepidermoid carcinoma (MEC), in comparison with normal tissues. MATERIALS AND METHODS: The TaqMan Human miRNA Cards Array was used for the miRNA profiling of MEC and normal tissues. To validate the differentially expressed miRNAs in MEC, we used real-time PCR (qRT-PCR). RESULTS: miR-302a was the most significantly increased miRNA in cancer tissues (p < .05). Here, we demonstrate that the upregulation of miR-302a expression in SGT cell lines induced cancer cell invasion in vitro. CONCLUSIONS: These promising results suggest the need for further studies to establish mir-302a as a marker of invasion and aggressiveness in MEC.

Combined effect of individual and neighborhood socioeconomic status on mortality in patients with newly diagnosed dyslipidemia: A nationwide Korean cohort study from 2002 to 2013.

BACKGROUND AND AIM: The study aims to determine whether dyslipidemia patients living in less affluent neighborhood are at a higher risk of mortality compared to those living in more affluent neighborhoods. METHODS AND RESULTS: A population-based cohort study was conducted using a stratified representative sampling from the National Health Insurance claim data from 2002 to 2013. The target subjects comprise patients newly diagnosed with dyslipidemia receiving medication. We performed a survival analysis using the Cox proportional hazard model. Of 11,946 patients with dyslipidemia, 1053 (8.8%) subjects died during the follow-up period. Of the dyslipidemia patients earning a middle-class income, the adjusted HR in less affluent neighborhoods was higher than that in the more affluent neighborhoods compared to the reference category of high individual SES in more affluent neighborhoods (less affluent; hazard ratio (HR) = 1.64, 95% confidence interval (CI): 1.35-1.99 vs. more affluent; HR = 1.48, 95% CI: 1.20-1.81, respectively). We obtained consistent results in patients with lower income, wherein the adjusted HR in less affluent neighborhoods was higher than that in more affluent neighborhoods (less affluent; HR = 1.52, 95% CI: 1.16-1.97 vs. more affluent; HR = 1.41, 95% CI: 1.04-1.92, respectively). CONCLUSION: Living in a less affluent neighborhood contributes to higher mortality among dyslipidemia patients. The individual- and neighborhood-level variables cumulatively affect individuals such that the most at-risk individuals include those having both individual- and neighborhood-level risk factors. These findings raise important clinical and public health concerns and indicate that neighborhood SES approaches should be essentially considered in health-care policies similar to individual SES.

Persistence of hAQP1 expression in human salivary gland cells following AdhAQP1 transduction is associated with a lack of methylation of hCMV promoter.

In 2012, we reported that 5 out of 11 subjects in a clinical trial (NCT00372320) administering AdhAQP1 to radiation-damaged parotid glands showed increased saliva flow rates and decreased symptoms over the initial 42 days. AdhAQP1 is a first-generation, E1-deleted, replication-defective, serotype 5 adenoviral vector encoding human aquaporin-1 (hAQP1). This vector uses the human cytomegalovirus enhancer/promoter (hCMVp). As subject peak responses were at times much longer (7-42 days) than expected, we hypothesized that the hCMVp may not be methylated in human salivary gland cells to the extent previously observed in rodent salivary gland cells. This hypothesis was supported in human salivary gland primary cultures and human salivary gland cell lines after transduction with AdhAQP1. Importantly, hAQP1 maintained its function in those cells. Conversely, when we transduced mouse and rat cell lines in vitro and submandibular glands in vivo with AdhAQP1, the hCMVp was gradually methylated over time and associated with decreased hAQP1 expression and function in vitro and decreased hAQP1 expression in vivo. These data suggest that the hCMVp in AdhAQP1was probably not methylated in transduced human salivary gland cells of responding subjects, resulting in an unexpectedly longer functional expression of hAQP1.

Establishment of functional acinar-like cultures from human salivary glands.

Disorders of human salivary glands resulting from therapeutic radiation treatment for head and neck cancers or from the autoimmune disease Sjögren syndrome (SS) frequently result in the reduction or complete loss of saliva secretion. Such irreversible dysfunction of the salivary glands is due to the impairment of acinar cells, the major glandular cells of protein, salt secretion, and fluid movement. Availability of primary epithelial cells from human salivary gland tissue is critical for studying the underlying mechanisms of these irreversible disorders. We applied 2 culture system techniques on human minor salivary gland epithelial cells (phmSG) and optimized the growth conditions to achieve the maintenance of phmSG in an acinar-like phenotype. These phmSG cells exhibited progenitor cell markers (keratin 5 and nanog) as well as acinar-specific markers-namely, α-amylase, cystatin C, TMEM16A, and NKCC1. Importantly, with an increase of the calcium concentration in the growth medium, these phmSG cells were further promoted to acinar-like cells in vitro, as indicated by an increase in AQP5 expression. In addition, these phmSG cells also demonstrated functional calcium mobilization, formation of epithelial monolayer with high transepithelial electrical resistance (TER), and polarized secretion of α-amylase secretion after ß-adrenergic receptor stimulation. Taken together, suitable growth conditions have been established to isolate and support culture of acinar-like cells from the human salivary gland. These primary epithelial cells can be useful for study of molecular mechanisms involved in regulating the function of acinar cells and in the loss of salivary gland function in patients.

Effects of in ovo injection with selenium on immune and antioxidant responses during experimental necrotic enteritis in broiler chickens.

This study was conducted to investigate the effects of in ovo injection of Se on modulating the immune system and antioxidant responses in broiler chickens with experimental necrotic enteritis. Broiler eggs were injected at 18 d of embryo age with either 100 µL of PBS alone or sodium selenite (Na2SeO3) in PBS, providing 0 (SS0), 10 (SS10), or 20 (SS20) µg of Se/egg. At 14 d posthatch, PBS-treated and uninfected chickens were kept as the control group, whereas the remaining chickens were orally infected with 1.0 × 10(4) sporulated oocysts of Eimeria maxima (SS0, SS10, SS20). At 18 d posthatch, E. maxima-infected chickens were orally infected with 1.0 × 10(9) cfu of Clostridium perfringens. Infected control SS0 group showed significantly decreased BW compared with the uninfected control. However, SS20 group showed significantly increased BW compared with the infected control SS0 group, whereas the BW were similar among uninfected control and infected SS10 and SS20 groups. The SS10 group showed significantly lower intestinal lesions compared with the SS0 group, and oocyst production was decreased in both SS10 and SS20 groups. Serum malondialdehyde level and catalase activity were also decreased in both SS10 and SS20 groups, whereas the superoxide dismutase level was significantly lower in the SS10 group compared with the SS0 group. The SS20 group showed significantly higher levels of transcripts for IL-1ß and IL-6 in intestine, and SS10 and SS20 groups had higher levels of transcripts for IL-8 and inducible nitric oxide synthase expression and decreased glutathione peroxidase 7 mRNA levels compared with the SS0 group. The SS10 and SS20 groups also showed increased serum antibody levels to C. perfringens α-toxin and NetB toxin compared with the SS0 group. These collective results suggest that the injection of Se into the amniotic cavity of developing eggs may be beneficial for enhancing immune and antioxidant responses in the hatched chickens exposed to the necrotic enteritis-causing pathogens.

Porcine feasibility and safety study of a new paclitaxel-eluting biliary stent with a Pluronic-containing membrane.

BACKGROUND AND STUDY AIM: Metal stents for malignant biliary obstruction are susceptible to occlusion by tumor ingrowth or overgrowth. Therefore, we previously reported our use of a metal stent covered with a paclitaxel-incorporated membrane giving an antitumor effect to prevent occlusion from tumor ingrowth. We have also developed a new generation of paclitaxel-eluting biliary stent using a membrane containing Pluronic F-127 for effective drug delivery. The aim of this study was to investigate the safety and efficacy of drug delivery for this newly developed stent in the biliary tract. METHODS: Metal stents were coated with paclitaxel and various concentrations of Pluronic F-127 in phosphate-buffered saline solution. Stents containing varying concentrations were placed in the bile ducts of eight pigs divided as follows: group I, 0% Pluronic + 0% paclitaxel; group II, 0% Pluronic + 10% paclitaxel; group III, 10% Pluronic + 10% paclitaxel; group IV, 20% Pluronic + 10% paclitaxel. The histology of the porcine bile duct and the amount of paclitaxel in the porcine serum were examined. The amount of paclitaxel released was also measured in vitro. RESULTS: Histologic changes in the porcine biliary epithelium were acceptable in terms of safety, based on inflammatory cell infiltration and fibrotic reaction. No significant differences in histology were observed between the groups. In the porcine serum analysis, released paclitaxel was detected for 28 days with the 10% Pluronic concentration (group III). However, released paclitaxel was observed for only 7 days in groups II and IV. In the in vitro experiments, long-lasting release of paclitaxel was also noted from the stent with 10% Pluronic. CONCLUSIONS: The new paclitaxel-eluting stent with 10% Pluronic F-127 is safe and provides enhanced local drug delivery.

In vitro effects of plant and mushroom extracts on immunological function of chicken lymphocytes and macrophages.

1. The present study was conducted to examine the effects of organic extracts from milk thistle (Silybum marianum), turmeric (Curcuma longa), reishi mushroom (Ganoderma lucidum), and shiitake mushroom (Lentinus edodes) on innate immunity and tumor cell viability. 2. Innate immunity was measured by lymphocyte proliferation and nitric oxide production by macrophages, and the inhibitory effect on tumor cell growth was assessed using a non-radioactive assay. For measuring the cytokine levels in the HD11 macrophages which were treated with extracts of turmeric or shiitake mushroom, the levels of mRNAs for interferon-alpha (IFN- alpha), interleukin-1beta (IL-1beta), IL-6, IL-12, IL-15, IL-18, and tumor necrosis factor superfamily 15 (TNFSF15) were quantified by real time RT-PCR. 3. In vitro culture of chicken spleen lymphocytes with extracts of milk thistle, turmeric, and shiitake and reishi mushrooms induced significantly higher cell proliferation compared with the untreated control cells. Stimulation of macrophages with extracts of milk thistle and shiitake and reishi mushrooms, but not turmeric, resulted in robust nitric oxide production to levels that were similar with those induced by recombinant chicken interferon-gamma. All extracts uniformly inhibited the growth of chicken tumor cells in vitro at the concentration of 6.3 through 100 microg/ml. Finally, the levels of mRNAs encoding IL-1beta, IL-6, IL-12, IL-18, and TNFSF15 were enhanced in macrophages that were treated with extracts of turmeric or shiitake mushroom compared with the untreated control. 4. These results document the immunologically-based enhancement of innate immunity in chickens by extracts of plants and mushrooms with known medicinal properties in vitro. In vivo studies are being planned to delineate the cellular and molecular mechanisms responsible for their mechanism of action.

High-throughput gene expression analysis of intestinal intraepithelial lymphocytes after oral feeding of carvacrol, cinnamaldehyde, or Capsicum oleoresin.

Among dietary phytonutrients, carvacrol, cinnamaldehyde, and Capsicum oleoresin are well known for their antiinflammatory and antibiotic effects in human and veterinary medicine. To further define the molecular and genetic mechanisms responsible for these properties, broiler chickens were fed a standard diet supplemented with either of the 3 phytochemicals and intestinal intraepithelial lymphocytes were examined for changes in gene expression by microarray analysis. When compared with chickens fed a nonsupplemented standard diet, carvacrol-fed chickens showed altered expression of 74 genes (26 upregulated, 48 downregulated) and cinnamaldehyde led to changes in the levels of mRNAs corresponding to 62 genes (31 upregulated, 31 downregulated). Most changes in gene expression were seen in the Capsicum-fed broilers with 98 upregulated and 156 downregulated genes compared with untreated controls. Results from the microarray analysis were confirmed by quantitative real-time PCR with a subset of selected genes. Among the genes that showed >2.0-fold altered mRNA levels, most were associated with metabolic pathways. In particular, with the genes altered by Capsicum oleoresin, the highest scored molecular network included genes associated with lipid metabolism, small molecule biochemistry, and cancer. In conclusion, this study provides a foundation to further investigate specific chicken genes that are expressed in response to a diet containing carvacrol, cinnamaldehyde, or Capsicum oleoresin.

Characterization of fibroblasts with Son of Sevenless-1 mutation.

Although non-syndromic hereditary gingival fibromatosis (HGF) is genetically heterogeneous, etiologic mutations have been identified only in the Son of Sevenless-1 gene (SOS1). To test evidence of increased cell proliferation, we studied histological, morphological, and proliferation characteristics in monolayer and three-dimensional cultures of fibroblasts with the SOS1 g.126,142-126,143insC mutation. Histological assessment of HGF gingiva indicated increased numbers of fibroblasts (30%) and increased collagen (10%). Cell proliferation studies demonstrated increased growth rates and 5-bromo-2-deoxyuridine incorporation for HGF fibroblasts. Flow cytometry showed greater proportions of HGF fibroblasts in the G2/M phase. Attachment of HGF fibroblasts to different extracellular matrix surfaces demonstrated increased formation of protrusions with lamellipodia. HGF fibroblasts in three-dimensional culture showed greater cell proliferation, higher cell density, and alteration of surrounding collagen matrix. These findings revealed that increased fibroblast numbers and collagen matrix changes are associated with mutation of the SOS1 gene in vitro and in vivo.

In vitro cytotoxicity of Mokko lactone in human leukemia HL-60 cells: induction of apoptotic cell death by mitochondrial membrane potential collapse.

We studied the effect of mokko lactone (ML) isolated from the roots of Saussurea lappa (Compositae), a plant that is used for medicinal purposes in Korea, on the induction of apoptosis in human leukemia HL-60 cells. ML was cytotoxic to HL-60 cells, and this cytotoxic effect of ML appears to be attributable to its induction of apoptotic cell death, as ML induced nuclear morphologic changes and internucleosomal DNA fragmentation and increased the proportion of Annexin V-positive cells and the activity of caspase-3. Further studies revealed that the induction of apoptosis by ML was associated with the loss of mitochondrial membrane potential. Collectively, our results suggest that apoptosis induced by ML in HL-60 cells was executed by a collapse of mitochondrial membrane potential followed by the activation of caspase-3. This is the first report on the mechanism of apoptosis-inducing effect of ML.

Hepatoprotective effect of baicalin, a major flavone from Scutellaria radix, on acetaminophen-induced liver injury in mice.

The protective effects of baicalin (BA), a major flavone from Scutellaria radix, on acetaminophen (AP)-induced hepatotoxicity and the possible mechanism(s) of its protective action were investigated in mice. Treatment with BA (300 mg/kg, p.o.) 0.5 h after AP administration significantly prevented an increase in plasma alanine aminotransferase and aspartate aminotransferase activities and AP-induced hepatic necrosis, and also reduced AP-induced mortality from 43% to 0%. In addition, oral treatment with BA significantly prevented AP-induced depletion of glutathione (GSH) contents. However, BA treatment, by itself, did not affect hepatic GSH contents. The effect of BA on the cytochrome P450 2E1 (CYP2E1), the major isozyme involved in AP bioactivation, was investigated. Oral treatment of mice with BA resulted in a significant decrease in AP-induced CYP2E1 activity together with its inhibition of AP-induced CYP2EI expression. These results show that the hepatoprotective effects of BA against AP overdose may be due to its ability to block the bioactivation of AP by inhibiting CYP2E1 expression.

Inhibitory effects of the stem bark of Catalpa ovata G. Don. (Bignoniaceae) on the productions of tumor necrosis factor-alpha and nitric oxide by the lipopolisaccharide-stimulated RAW 264.7 macrophages.

In order to validate the use of the stem bark of Catalpa ovata G. Don. (Bignoniaceae) as an anti-inflammatory drug in the traditional Korean medicine, we have investigated the effects of the methanol extract of this folk medicine on the productions of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) on RAW 264.7 macrophages activated with the endotoxin lipopolysaccharide. The extract inhibited the productions of TNF-alpha and NO with significant decreases in mRNA levels of TNF-alpha and inducible NO synthase, suggesting that the stem bark of Catalpa ovata may have therapeutic potential in the control of inflammatory disorders.

Salidroside from Rhodiola sachalinensis protects neuronal PC12 cells against cytotoxicity induced by amyloid-beta.

The amyloid beta-peptide (Abeta)-induced oxidative stress is a well-established pathway of neuronal cell death in Alzheimer's disease (AD). Salidroside, one of the major compounds from the roots of Rhodiola species (Crassulaceae), was investigated in vitro for its cytoprotection against Abeta-induced toxicity on rat neuronal PCl2 cells. Salidroside significantly reduced Abeta-induced cytotoxicity in a dose-dependent manner. Salidroside also reduced Abeta-mediated intracellular accumulation of reactive oxygen species and malondialdehyde (MDA), a product of lipid peroxides, by preventing Abeta-induced decline of antioxidant enzyme activities. These results suggest that salidroside protects neuronal PC12 cells from Abeta-induced cytotoxicity via its antioxidant pathway.

Inhibition of TNF-alpha, IL-1beta, and IL-6 productions and NF-kappa B activation in lipopolysaccharide-activated RAW 264.7 macrophages by catalposide, an iridoid glycoside isolated from Catalpa ovata G. Don (Bignoniaceae).

Catalposide, the major iridoid glycoside isolated from the stem bark of Catalpa ovata G. Don (Bignoniaceae), was found to inhibit the productions of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6), and the activation of nuclear factor kappaB (NF-kappaB) in RAW 264.7 macrophages activated with lipopolysaccharide (LPS). Catalposide also inhibited the expressions of TNF-alpha, IL-1beta, and IL-6 genes and the nuclear translocation of p65 subunit of NF-kappaB in LPS-activated RAW 264.7 cells. Flow cytometric analysis revealed that catalposide suppressed the binding of FITC-conjugated LPS to CD14 on the surface of cells, probably resulting in the inhibitory effects on TNF-alpha, IL-1beta, and IL-6 productions and NF-kappaB activation. These findings suggest that catalposide could be an attractive candidate for adjunctive therapy in gram-negative bacterial infections.

Complex interactions between epidermal POU domain and activator protein 1 transcription factors regulate the expression of the profilaggrin gene in normal human epidermal keratinocytes.

The human profilaggrin gene is expressed in the granular layer during the late stages of the epidermal differentiation. The proximal promoter region of the gene confers high levels of keratinocyte-specific transcription via interactions with c-Jun/c-Fos heterodimers. Here we provide evidence for another level of complexity in the regulation of the profilaggrin promoter activity. The POU domain proteins Oct1, Skn1a/i, and Oct6, which are abundantly expressed in the epidermal cells, act to both stimulate and repress transcription in a general and a cell type-specific mode. While binding to specific recognition elements within the promoter region, they exert their effects by either stimulating or antagonizing the c-Jun-dependent activity of the promoter. The response of the promoter to forced expression of the POU domain proteins reflects the effect of these transcription factors on the endogenous profilaggrin mRNA synthesis and suggests that the latter requires a fine balance in the amounts and the activities of the individual activator protein 1 and POU domain proteins.

The expression of a novel, epithelium-specific ets transcription factor is restricted to the most differentiated layers in the epidermis.

Ets proteins have been implicated in the regulation of gene expression during a variety of biological processes, including growth control, differentiation, development and transformation. More than 35 related proteins containing the 'ets domain' have now been found which specifically interact with DNA sequences encompassing the core tetranucleotide GGAA. Although ets responsive genes have been identified in the epidermis, little is known about their distribution and function in this tissue. We have now demonstrated that epidermis and cultured epidermal keratinocytes synthesize numerous ets proteins. The expression of some of these proteins is regulated as a function of differentiation. Among these is a novel ets transcription factor with a dual DNA-binding specificity, which we have called jen. The expression of jen is not only epithelial specific, but it is the only ets protein so far described, and one of the very few transcription factors whose expression is restricted to the most differentiated epidermal layers. We show that two epidermal marker genes whose expression coincides with that of jen are transregulated by this protein in a complex mode which involves interactions with other transcriptional regulators such as Sp1 and AP1.

Opposing activities of c-Fos and Fra-2 on AP-1 regulated transcriptional activity in mouse keratinocytes induced to differentiate by calcium and phorbol esters.

The major differentiation products of maturing keratinocytes contain AP-1 regulatory motifs, and AP-1 DNA binding activity increases in cultured keratinocytes induced to differentiate by calcium. Here, we have analysed AP-1 transcriptional activity in mouse keratinocytes treated with calcium and 12-O-tetradecanoyl phorbol-13-acetate (TPA), two agents that induce terminal differentiation of keratinocytes with different phenotypic consequences. Reporter constructs representing multimers of AP-1 sequences found in keratinocyte marker genes demonstrated that the calcium-induced AP-1 DNA binding activity does not correlate with transcriptional activation. Moreover, expression from active subunits of the profilaggrin and spr 1 promoters increased in calcium-treated keratinocytes when the AP-1 sites were disrupted, indicating that AP-1 may negatively regulate certain promoters in these cells. In contrast, AP-1 reporter activity was increased in keratinocytes treated with TPA. This induction was dependent upon the expression of c-Fos since AP-1 transcriptional activity was not increased in TPA-treated keratinocytes derived from c-fos null mice. Analysis of AP-1 protein expression in calcium- and TPA-treated keratinocytes demonstrated that only TPA increased the expression of c-Jun, while Jun B and Jun D were induced by both of these agents. c-Fos was expressed only in TPA treated keratinocytes, Fra-2 was expressed only in calcium-treated cells, and Fra-1 was expressed in both. Exogenous expression of Fra-2 repressed AP-1 transcriptional activity in TPA-treated keratinocytes, while c-Fos expression activated the AP-1 sequence in calcium-treated keratinocytes. These data indicate that Fra-2 and c-Fos play opposing roles in regulating AP-1 activity in keratinocytes and that multiple inducer-dependent regulatory pathways may exist for the expression of keratinocyte differentiation markers.