This model is null for both products of the Cdkn2a locus, p16INK4A and p19ARF, mirroring this common lesion in human melanomas, and it carries the HRAS transgene under control of the tyrosinase promoter, activating the MAPK pathway, as occurs in human melanomas through NRAS or BRAF mutation. The gene discussed is NRAS; the disease is melanoma.