Repressor Proteins/metabolism; Trans-Activators/metabolism; Animals; Basal Cell Nevus Syndrome/genetics; Basal Cell Nevus Syndrome/metabolism; Basal Cell Nevus Syndrome/pathology; Cyclic AMP-Dependent Protein Kinases/antagonists & inhibitors; Disease Models, Animal; Embryonic Development/genetics; Female; Fibroblasts/metabolism; Gene Expression Regulation, Developmental; Green Fluorescent Proteins/genetics; Green Fluorescent Proteins/metabolism; Hedgehog Proteins; Humans; Intracellular Signaling Peptides and Proteins/deficiency; Intracellular Signaling Peptides and Proteins/genetics; Kruppel-Like Transcription Factors/genetics; Kruppel-Like Transcription Factors/metabolism; Membrane Proteins/deficiency; Membrane Proteins/genetics; Mice; Mice, Knockout; Mice, Mutant Strains; Nervous System/embryology; Patched Receptors; Phenotype; Pregnancy; Receptors, Cell Surface; Receptors, G-Protein-Coupled/agonists; Receptors, G-Protein-Coupled/antagonists & inhibitors; Recombinant Fusion Proteins/genetics; Recombinant Fusion Proteins/metabolism; Repressor Proteins/genetics; Signal Transduction; Skin/metabolism; Skin/pathology; Smoothened Receptor; Zinc Finger Protein GLI1