Cell Cycle/drug effects; Coumarins/pharmacology; Enzyme Inhibitors/pharmacology; Folic Acid Antagonists/pharmacology; Melanoma/pathology; Polyglutamic Acid/metabolism; Thymidylate Synthase/antagonists & inhibitors; Apoptosis/drug effects; Blotting, Western; Caspase 3/metabolism; Cell Cycle/genetics; Cell Line, Tumor; Coumarins/chemistry; Coumarins/therapeutic use; Cyclin D1/metabolism; Cyclin-Dependent Kinase Inhibitor p21/metabolism; Enzyme Inhibitors/chemistry; Enzyme Inhibitors/therapeutic use; Folic Acid Antagonists/chemistry; Folic Acid Antagonists/therapeutic use; G1 Phase Cell Cycle Checkpoints/drug effects; Gene Expression Regulation, Neoplastic/drug effects; Humans; Melanoma/drug therapy; Melanoma/enzymology; Melanoma/genetics; Models, Biological; Phosphorylation/drug effects; RNA, Messenger/genetics; RNA, Messenger/metabolism; Retinoblastoma Protein/metabolism; Signal Transduction/drug effects; Thymidylate Synthase/metabolism; Tumor Suppressor Protein p53/metabolism