Melanoma/genetics; Melanoma/pathology; Neural Crest/enzymology; Oxidoreductases Acting on CH-CH Group Donors/metabolism; Transcription, Genetic; Amino Acid Substitution; Animals; Animals, Genetically Modified; Cell Differentiation/drug effects; Cell Line, Tumor; Cell Lineage/drug effects; Dihydroorotate Dehydrogenase; Disease Models, Animal; Gene Expression Regulation, Neoplastic; Genes, p53/genetics; Humans; Isoxazoles/pharmacology; Isoxazoles/therapeutic use; Leflunomide; Melanoma/drug therapy; Melanoma/enzymology; Mice; Neural Crest/drug effects; Neural Crest/metabolism; Neural Crest/pathology; Oxidoreductases Acting on CH-CH Group Donors/antagonists & inhibitors; Proto-Oncogene Proteins B-raf/antagonists & inhibitors; Proto-Oncogene Proteins B-raf/chemistry; Proto-Oncogene Proteins B-raf/genetics; Proto-Oncogene Proteins B-raf/metabolism; Rats; Stem Cells/cytology; Stem Cells/drug effects; Stem Cells/pathology; Transcription, Genetic/drug effects; Transcription, Genetic/physiology; Xenograft Model Antitumor Assays; Zebrafish/embryology; Zebrafish/genetics