These models included a fibrosarcoma model, in which 3-methylcholanthrene was applied once; a skin papilloma model, in which mice were inoculated subcutaneously with 7,12-dimethylbenz[a]anthracene (DMBA) once, which was followed by repeated application of 12-O-tetradecanoylphorbol-13-acetate (TPA); and a melanoma mouse model, in which cannabinoid receptor double knockout mice were crossed with melanoma-prone Hgf-Cdk4R24C mice, with melanoma growth induced by a single epicutaneous application of DMBA. This evidence concerns the gene HGF and melanoma.