Explainable artificial intelligence analysis of brachytherapy boost receipt in cervical cancer during the COVID-19 era.

PURPOSE: Brachytherapy is a critical component of the standard-of-care curative radiotherapy regimen for women with locally advanced cervical cancer (LACC). However, existing literature suggests that many patients will not receive the brachytherapy boost. We used machine learning (ML) and explainable artificial intelligence to characterize this disparity. MATERIALS AND METHODS: Patients with LACC diagnosed from 2004 to 2020 who received definitive radiation were identified in the National Cancer Database. Five ML models were trained to predict if a patient received a brachytherapy boost. The best-performing model was explained using SHapley Additive exPlanation (SHAP) values. To identify trends that may be attributable to the coronavirus disease 2019 (COVID-19) pandemic, the previous analysis was repeated and limited to 2019 to 2020. RESULTS: A total of 37,564 patients with LACC were identified; 5799 were diagnosed from 2019 to 2020 (COVID cohort). Of these patients, 59.3% received a brachytherapy boost, with 76.4% of patients diagnosed in 2019 to 2020 receiving a boost. The random forest model achieved the best performance for both the overall and COVID cohorts. In the overall cohort, the most important predictive features were the year of diagnosis, stage, age, and insurance status. In the COVID cohort, the most important predictive features were FIGO stage, age, insurance status, and hospital type. Of the 26 patients who tested positive for COVID-19 during their course of radiotherapy, 19 (73.1%) received a brachytherapy boost. CONCLUSIONS: A gradual increase in brachytherapy boost utilization has been noted, which did not seem to be significantly impacted by the onset of the COVID-19 pandemic. ML could be considered to identify patient populations where brachytherapy is underutilized, which can provide actionable feedback for improving access.

Comparison of baseline drifts using three reflector blocks versus using a single reflector block for the calibration of wall-mounted Respiratory Gating for Scanner (RGSC) camera integrated with a CT.

BACKGROUND: The calibration of the Respiratory Gating for SCanner (RGSC) system is critical to achieve better and more stable accuracy. The current procedure for a wall-mounted RGSC system has a relatively large residual error. PURPOSE: To compare the baseline drifts in the image acquisition of DIBH using three reflector blocks versus using a single reflector block in the calibration of a wall-mounted RGSC camera system. MATERIALS AND METHODS: Varian provides a calibration plate with three rows of calibration points: each row is separated by 15 cm longitudinally and by 10 cm laterally. In Varian's single-block calibration method, the reflector block was first placed on the center point of the calibration plate and aligned with the scanner isocenter. The calibration took a picture of the block, then placed the block on the other eight points sequentially. In the proposed three-block method, we placed three reflector blocks on the center row, with the center block aligned with the isocenter, and we took a picture of the center block by manually blocking the other two blocks in calibration. By moving the couch longitudinally in or out 15 cm, the calibration goes through all nine points. Monte Carlo simulation was done using Matlab to analyze the calibration matrix eigenvalue characteristics. RESULTS: For a typical scan length of 40 cm of DIBH, the residual baseline drift in simulated DIBH is 0.02 ± 0.03  versus 0.30 ± 0.12 cm for three-block calibration and single-block calibration, respectively. To achieve 0.5 mm tolerance for the eigenvalue, the laser and reflector box should be within ±3 mm uncertainties based on the eigenvalue simulation. CONCLUSION: Three-block calibration method effectively removes baseline drift caused by couch movement in DIBH/4D CT scan for the wall-mounted camera while the single-block calibration method still has significant residual baseline drift.

The Emerging Role of Radiotherapy in Oligoprogressive Non-Small Cell Lung Cancer.

Oligoprogressive disease (OPD) is an emerging concept that describes patients who have progression of disease in a limited number of metastatic sites while on systemic therapy. Growing evidence has suggested the integration of local ablative therapy with systemic agents in patients with OPD further improves survival. In oligoprogressive non-small cell lung cancer, stereotactic body radiotherapy may have an important role in the effective local control of selective progressing metastases, which may translate to better patient outcomes. This review explores the treatment paradigm of this subset of patients and provides an update on the current existing literature on this topic.

Successful novel use of tofacitinib for type II refractory coeliac disease.

Refractory coeliac disease (RCD) occurs when patients with confirmed CD have continuous or recurrent malabsorption and enteropathy after at least 12 months on a gluten-free diet. Differentiating between type I and type II RCD is key as the latter is associated with T-cell aberrancy and considered prelymphoma, with high mortality rates. Current treatment regimens for type II RCD include corticosteroids, biologics and chemotherapy, but there are no proven therapies for this serious condition. Our patient is a middle-aged woman who developed postpartum type II RCD. When she failed multiple drug classes, we did a trial of tofacitinib. Our clinical experience with use of a janus kinase inhibitor was successful, with no associated adverse events. This is the first report in the literature of RCD remission in response to tofacitinib. The use of this novel agent shows promise in reversing this potentially fatal condition.

Language proficiency and biologics access: a population study of psoriasis patients in the United States.

BACKGROUND: Language proficiency plays an important role in healthcare choices and access. Differences in access to biologic medications exist, but it is unknown how much English proficiency influences access in US psoriasis patients. OBJECTIVE: To compare biologic medication use for psoriasis patients with differing English proficiency levels. METHODS: Population study of US psoriasis patients using the 2013-2017 Medical Expenditure Survey. RESULTS: Among a total of 4,470,820 US psoriasis patients (weighted), 4,028,119 (90.1%) had perfect English proficiency, and 442,700 (9.9%) had less than perfect English proficiency. Among the total population, 422,523 (9.5%) had access to biologics. Among those who received biologics, 411,411 (97.4%) of those had perfect English proficiency, and 11,112 (2.6%) of those had less than perfect English proficiency. Multivariate logistic regression found that patients with less than perfect English proficiency were significantly less likely to have access to biologics [OR 0.015 (95% CI: 0.001-0.179); p = .002], after adjusting for insurance status, income, education, healthcare utilization, and other sociodemographic and clinical factors. LIMITATIONS: Psoriasis disease severity not specified. CONCLUSIONS: Psoriasis patients with low English proficiency are significantly less likely to receive biologics than those with high English proficiency. Those with higher English proficiency are 61 times more likely to access biologics.

Differences in health care resource utilization and costs for keratinocyte carcinoma among racioethnic groups: A population-based study.

BACKGROUND: As the United States becomes more diverse, determining differences in health care utilization and costs in the management of skin cancers is fundamental to decision-making in health care resource allocation and improving care for underserved populations. OBJECTIVE: To compare health care use and costs among non-Hispanic White, Hispanic White, and non-Hispanic Black patients with keratinocyte carcinoma. METHODS: A nationwide cross-sectional study was performed using Medical Expenditure Panel Survey data from 1996 to 2015. RESULTS: Among 54,503,447 patients with keratinocyte carcinoma (weighted) over a 20-year period, 53,134,351 (97%) were non-Hispanic White; 836,030 (1.5%) were Hispanic White; and 170,755 (0.3%) were non-Hispanic Black. Compared to non-Hispanic White patients, Hispanic White patients had significantly more ambulatory visits per person per year (5.4 vs 3.5, P = .003). Compared to non-Hispanic White patients, non-Hispanic Black patients had significantly more ambulatory visits (13.1 vs 3.5, P = .027) and emergency department visits (2.3 vs 1.1, P < .001), and incurred significantly higher ambulatory costs ($5089 vs $1131, P = .05), medication costs ($523 vs $221, P = .022), and total costs per person per year ($13,430 vs $1290, P = .032). LIMITATIONS: Data for squamous cell carcinomas and basal cell carcinomas are combined. CONCLUSIONS: Keratinocyte carcinoma was more costly to treat and required more health care resources in non-Hispanic Black and Hispanic White patients than in non-Hispanic White patients.

Expression of immune checkpoint regulators, cytotoxic T lymphocyte antigen 4 (CTLA-4), and CD137 in cervical carcinoma.

Immune checkpoint inhibitors have a significant role in oncology. One of these immune checkpoints is cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). Inhibition of the CTLA-4 pathway has already led to the FDA approval of Ipilimumab (anti-CTLA-4), a targeted therapy for melanoma and other malignancies. CD137 is an inducible, costimulatory receptor of the tissue-necrosis-factor-receptor superfamily expressed on the activated immune cells. Clinical trials have also been set for anti-CD137 in several malignancies. We assessed CTLA-4 and CD137 expression on a tissue microarray (TMA) comprising of 99 core tissues which included normal, non-neoplastic, and neoplastic cervical lesions. When detected as strong granular cytoplasmic reaction in the epithelial cells, CTLA-4 expression was scored as positive. For CD137, the results were recorded based on the presence or absence of staining reaction on the cell membranes of the lymphoplasmacytic infiltrates. Overall, CTLA-4 was positive in 30% (30/100) of the cervical malignancies. Sub-categorically, 20% of invasive endocervical adenocarcinomas, 63% of adenosquamous carcinomas, and 31% of squamous cell carcinomas were positive for CTLA-4 with a tendency toward lower grade squamous cell carcinomas (SCCs). CD137 was positive in 100% lymphoplasmacytic infiltrates of endocervical adenocarcinomas, 90.5% of SCCs, and 87.5% of adenosquamous carcinomas. This study has found a significant expression of CTLA-4 in cervical cancer cells and CD137 positivity of lymphoplasmacytic infiltrates with potential for future targeted immunotherapy.

Brodalumab in an Organ Transplant Recipient With Psoriasis.

Immunocompromised patients, such as organ transplant recipients, require careful benefit-risk consideration when selecting a systemic agent for psoriasis. Brodalumab is an immunomodulatory biologic that binds to and inhibits IL-17RA, thereby inhibiting the actions of IL-17A, F, E, and C. Brodalumab has a rapid onset of action, sustained efficacy, and an acceptable safety profile, all of which serve to enhance its appeal as a systemic treatment option for psoriasis in immunocompromised patients. Reports of brodalumab use for psoriasis in organ transplant recipients are limited. We report a case in which brodalumab was used to treat psoriasis in a patient who had undergone solid organ transplantation with excellent response and good tolerability.

Differences in Depression and Distress Between Acne Patients on Isotretinoin vs Oral Antibiotics.

BACKGROUND: Little is known regarding differential effects of systemic anti-acne treatments on mental health. OBJECTIVE: To determine whether differences exist in mental health outcomes between acne patients treated with isotretinoin versus oral antibiotics (doxycycline, minocycline, or tetracycline). METHODS: Population study utilizing the 2004-2017 Medical Expenditure Panel Survey. Depressive symptoms were assessed using Patient Health Questionnaire 2 (PHQ-2); psychological distress was measured by the Kessler 6-Item Psychological Distress Scale (K6). Acne patients completed both the PHQ-2 and K6 during treatment with isotretinoin or oral antibiotics. Lower scores on both measures indicate better mental health outcomes. RESULTS: After adjusting for socio-demographic characteristics, patients on isotretinoin had fewer depressive symptoms than patients on oral antibiotics, as measured by mean PHQ-2 scores (isotretinoin 0.280 vs oral antibiotics 0.656, difference=0.337, P<0.01). The adjusted comparison also showed patients on isotretinoin had less psychological distress than patients on oral antibiotics, as measured by K6 scores (isotretinoin 2.494 vs oral antibiotics 3.433, difference=0.759, P=0.043). LIMITATIONS: No direct assessment of acne severity. CONCLUSION: Acne patients on isotretinoin experienced less depressive symptoms and psychological distress as compared to oral antibiotics. J Drugs Dermatol. 2021;20(2):172-177. doi:10.36849/JDD.5559.

SMAD4-Expressing Pancreatic Ductal Adenocarcinomas Have Better Response to Neoadjuvant Therapy and Significantly Lower Lymph Node Metastasis Rates.

OBJECTIVE: For many patients whose pancreatic ductal adenocarcinoma (PDAC) is locally advanced, neoadjuvant therapy has been proposed as a way to decrease tumor burden. Pancreatic ductal adenocarcinoma is generally thought to be resistant to chemotherapy and radiation, however, response to neoadjuvant therapy in PDAC has been described in a subset of patients. The SMAD4 status is considered to be an important molecular feature which distinguishes two subsets of PDAC, SMAD4-positive and -negative tumors. The objective of this study was to evaluate the neoadjuvant treatment response rate as well as compare the different clinicopathologic variables between SMAD4-positive and -negative tumors. METHODS: We analyzed the data of patients who underwent surgical resection for PDAC from 2009-2019. Our cohort from a single institution included 233 patients. RESULTS: Of the 233 cases, 143 (61.4%) were SMAD4-negative and 90 (38.6%) were SMAD4-positive. Overall, SMAD4-positive tumors with neoadjuvant therapy had better treatment response and better tumor regression scores. In addition, SMAD4-positive tumors had a significantly lower lymph node metastasis rate in both the neoadjuvant and nonneoadjuvant setting. CONCLUSIONS: Further characterization of the role of SMAD4 within the context of neoadjuvant therapy will lead to improved personalized therapeutic strategies.

Acute hepatitis and acute liver failure: Pathologic diagnosis and differential diagnosis.

Acute hepatitis and acute liver failure are severe medical conditions that require early clinical intervention. Histopathologic findings on a liver biopsy or a liver explant may help identify the underlying etiology or provide an important direction for further clinical, laboratory and radiographical investigation. This review is divided into two main portions. The first portion concentrates on various etiologies and discusses unique histologic features that can be associated with specific etiologies. The second portion describes the general morphologic features based on which the diagnosis of acute hepatitis and acute liver failure are made. Histopathologic distinction between collapse and cirrhosis and limitations of histopathologic assessment for underlying etiologies are addressed in this portion. Another focus of this review is non-necrotic acute liver failure, which typically features diffuse microvesicular steatosis secondary to various etiologies causing mitochondrial dysfunction. Molecular testing serves an increasingly important role in the diagnosis and management of this group of disorders.

Impact of Changes in the American Joint Committee on Cancer Staging Manual, Eighth Edition, for Pancreatic Ductal Adenocarcinoma.

OBJECTIVE: Consistent and reliable tumor staging is a critical factor in determining treatment strategy, selection of patients for adjuvant therapy, and for therapeutic clinical trials. The aim of this study was to evaluate the number and extent of pancreatic ductal adenocarcinoma (PDAC) cases that would have a different pT, pN, and overall stages based on the new eighth edition American Joint Committee on Cancer staging system when compared with the seventh edition. METHODS: Patients diagnosed with PDAC who underwent pancreaticoduodenectomy, total pancreatectomy, or distal pancreatectomy from 2007 to 2017 were retrospectively reviewed. A total of 340 cases were included. RESULTS: According to the seventh edition, the vast majority of tumors in our cohort were staged as pT3 tumors (88.2%). Restaging these cases with the new size-based pT system resulted in a more equal distribution among the 3 pT categories, with higher percentage of pT2 cases (55%). CONCLUSIONS: The newly adopted pT stage protocol for PDAC is clinically relevant, ensures a more equal distribution among different stages, and allows for a significant prognostic stratification. In contrast, the new pN classification (pN1 and pN2) based on the number of positive lymph nodes failed to show survival differences and remains controversial.

Goblet Cell Carcinoid/Carcinoma: An Update.

Goblet cell carcinoid (GCC) or goblet cell carcinoma is a unique mixed endocrine-exocrine neoplasm that is almost exclusively seen in the appendix. The hallmark of GCC is the concentric infiltration of the appendiceal wall by small tight clusters, nests or cords of tumor cells that exhibit a goblet cell morphology with a small compressed nucleus and conspicuous intracytoplasmic mucin. The coexistence of high-grade adenocarcinoma with GCC has been increasingly recognized as a common finding, which has been called adenocarcinoma ex GCC or mixed GCC-adenocarcinoma. A number of studies have shown that it is the high-grade adenocarcinomatous component that dictates the prognosis. Several histologic classification/grading systems have been proposed, which correlate with overall patient survival. Treatment options are primarily based on tumor stage and the presence or absence of a high-grade adenocarcinomatous component.

Comparative Accuracy of Tumor Size Assessment and Stage Analysis by Imaging Modalities Versus Gross Examination for Pancreatic Ductal Adenocarcinoma.

OBJECTIVES: Tumor size has been shown to be a strong predictor of patient survival in pancreatic ductal adenocarcinoma (PDAC). The aims of this study were to assess the consistency of preoperative imaging and gross examination for PDAC tumor size measurement and to evaluate the impact on T and overall tumor staging when size measurements by imaging and gross examination were different. METHODS: Patients diagnosed with PDAC who underwent pancreaticoduodenectomy or distal pancreatectomy from 2007 to 2017 were retrospectively reviewed. A total of 268 cases were included. RESULTS: Imaging studies underestimated tumor size in comparison with gross examination. Staging the tumors based on imaging size using the eighth edition American Joint Committee on Cancer resulted in an altered T stage in 106 cases (39.6%). There was no T-stage change in the remaining 162 cases (60.4%) despite the presence of variable size discrepancies (0.1-1.7 cm). When nodal metastases were also considered, there was no change in the overall tumor stage in most cases. CONCLUSIONS: Although discrepancies exist between tumor size measurements by imaging modalities and gross examination, which may result in an altered T stage in a substantial number of cases, the overall tumor stage is only rarely altered.

c-Abl phosphorylation of Yin Yang 1's conserved tyrosine 254 in the spacer region modulates its transcriptional activity.

Yin Yang 1 (YY1) is a multifunctional transcription factor that can activate or repress transcription depending on the promotor and/or the co-factors recruited. YY1 is phosphorylated in various signaling pathways and is critical for different biological functions including embryogenesis, apoptosis, proliferation, cell-cycle regulation and tumorigenesis. Here we report that YY1 is a substrate for c-Abl kinase phosphorylation at conserved residue Y254 in the spacer region. Pharmacological inhibition of c-Abl kinase by imatinib, nilotinib and GZD824, knock-down of c-Abl using siRNA, and the use of c-Abl kinase-dead drastically reduces tyrosine phosphorylation of YY1. Both radioactive and non-radioactive in vitro kinase assays, as well as co-immunoprecipitation in different cell lines, show that the target of c-Abl phosphorylation is tyrosine residue 254. c-Abl phosphorylation has little effect on YY1 DNA binding ability or cellular localization in asynchronous cells. However, functional studies reveal that c-Abl mediated phosphorylation of YY1 regulates YY1's transcriptional ability in vivo. In conclusion, we demonstrate the novel role of c-Abl kinase in regulation of YY1's transcriptional activity, linking YY1 regulation with c-Abl tyrosine kinase signaling pathways.

Expression of immune checkpoint regulators, cytotoxic T lymphocyte antigen 4 (CTLA-4) and programmed death-ligand 1 (PD-L1), in female breast carcinomas.

BACKGROUND: Immune checkpoint regulators, cytotoxic T lymphocyte antigen 4 (CTLA-4) and the programmed cell death protein-1/programmed death-ligand 1 (PD-1/PD-L1) have emerged as promising new targets for cancer therapeutics. While tumor expression of PD-L1 has been shown to have objective responses to anti-PD-L1 immunotherapies, the clinical implications of CTLA-4 expression in tumor cells or immune cells in the tumor microenvironment is still controversial. We investigated the expression of CTLA-4 and PD-L1 in human breast tumors and provided a scoring system for the systematic evaluation of CTLA-4 staining. METHODS: Immunohistochemical staining for PD-L1 and CTLA-4 expression was performed on a tissue microarray of 102 cores, which included normal and neoplastic breast tissues. Neoplastic cores were divided into four groups: Ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC) and invasive tubular carcinoma (ITC). PD-L1 and CTLA-4 expressions were scored based on a system which accounted for the percentage and intensity of positivity and results provided in conjunction with available clinical and demographic data. RESULTS: Overall, CTLA-4 was over-expressed in 49 of 93 (52.7%) breast tumors. Subcategorically, CTLA-4 was positive in 3 of 8 (37.5%) ductal carcinoma in situ, 40 of 73 (55%) of invasive ductal carcinomas, 4 of 10 (40%) of invasive lobular carcinomas and 2 of 2 (100%) of invasive tubular carcinomas. All 6 normal breast tissues were interpreted as negative for CTLA-4 staining. Only 4.1% of the invasive ductal carcinomas were positive for PD-L1 reactivity and the remaining carcinomas stained negative. CONCLUSIONS: This study shows a significant overexpression of CTLA-4 in >50% of breast carcinomas with no such overexpression of CTLA-4 in benign breast tissues. PDL-1 staining is seen in only a small number of invasive ductal carcinomas (4.1%). These findings suggest the need for further investigation of anti-CTLA-4 and anti-PD-L1 immunotherapies and their efficacy in the treatment of breast carcinomas with overexpression of these immune modulators. In addition, the proposed scoring system will facilitate a more systematic correlation between tumor reactivity and clinical outcome which can be applied to all intracytoplasmic tumor markers.

The transcription factor YY1 is a novel substrate for Aurora B kinase at G2/M transition of the cell cycle.

Yin Yang 1 (YY1) is a ubiquitously expressed and highly conserved multifunctional transcription factor that is involved in a variety of cellular processes. Many YY1-regulated genes have crucial roles in cell proliferation, differentiation, apoptosis, and cell cycle regulation. Numerous mechanisms have been shown to regulate the function of YY1, such as DNA binding affinity, subcellular localization, and posttranslational modification including phosphorylation. Polo-like kinase 1(Plk1) and Casein kinase 2α (CK2 α) were the first two kinases identified to phosphorylate YY1. In this study, we identify a third kinase. We report that YY1 is a novel substrate of the Aurora B kinase both in vitro and in vivo. Serine 184 phosphorylation of YY1 by Aurora B is cell cycle regulated and peaks at G2/M and is rapidly dephosphorylated, likely by protein phosphatase 1 (PP1) as the cells enter G1. Aurora A and Aurora C can also phosphorylate YY1 in vitro, but at serine/threonine residues other than serine 184. We present evidence that phosphorylation of YY1 in the central glycine/alanine (G/A)-rich region is important for DNA binding activity, with a potential phosphorylation/acetylation interplay regulating YY1 function. Given their importance in mitosis and overexpression in human cancers, Aurora kinases have been identified as promising therapeutic targets. Increasing our understanding of Aurora substrates will add to the understanding of their signaling pathways.

Phosphorylation of the transcription factor YY1 by CK2α prevents cleavage by caspase 7 during apoptosis.

In this report, we describe the phosphorylation of Yin Yang 1 (YY1) in vitro and in vivo by CK2α (casein kinase II), a multifunctional serine/threonine protein kinase. YY1 is a ubiquitously expressed multifunctional zinc finger transcription factor implicated in regulation of many cellular and viral genes. The products of these genes are associated with cell growth, the cell cycle, development, and differentiation. Numerous studies have linked YY1 to tumorigenesis and apoptosis. YY1 is a target for cleavage by caspases in vitro and in vivo as well, but very little is known about the mechanisms that regulate its cleavage during apoptosis. Here, we identify serine 118 in the transactivation domain of YY1 as the site of CK2α phosphorylation, proximal to a caspase 7 cleavage site. CK2α inhibitors, as well as knockdown of CK2α by small interfering RNA, reduce S118 phosphorylation in vivo and enhance YY1 cleavage under apoptotic conditions, whereas increased CK2α activity by overexpression in vivo elevates S118 phosphorylation. A serine-to-alanine substitution at serine 118 also increases the cleavage of YY1 during apoptosis compared to wild-type YY1. Taken together, we have discovered a regulatory link between YY1 phosphorylation at serine 118 and regulation of its cleavage during programmed cell death.

The transcription factor YY1 is a substrate for Polo-like kinase 1 at the G2/M transition of the cell cycle.

Yin-Yang 1 (YY1) is an essential multifunctional zinc-finger protein. It has been shown over the past two decades to be a critical regulator of a vast array of biological processes, including development, cell proliferation and differentiation, DNA repair, and apoptosis. YY1 exerts its functions primarily as a transcription factor that can activate or repress gene expression, dependent on its spatial and temporal context. YY1 regulates a large number of genes involved in cell cycle transitions, many of which are oncogenes and tumor-suppressor genes. YY1 itself has been classified as an oncogene and was found to be upregulated in many cancer types. Unfortunately, our knowledge of what regulates YY1 is very minimal. Although YY1 has been shown to be a phosphoprotein, no kinase has ever been identified for the phosphorylation of YY1. Polo-like kinase 1 (Plk1) has emerged in the past few years as a major cell cycle regulator, particularly for cell division. Plk1 has been shown to play important roles in the G/M transition into mitosis and for the proper execution of cytokinesis, processes that YY1 has been shown to regulate also. Here, we present evidence that Plk1 directly phosphorylates YY1 in vitro and in vivo at threonine 39 in the activation domain. We show that this phosphorylation is cell cycle regulated and peaks at G2/M. This is the first report identifying a kinase for which YY1 is a substrate.