Cg-Tg (KRT14-Kitl*) 4XTG2Bjl/J mice, which express mutant mouse Kitl cDNA and possess abundant melanocytes in the epidermis, as well as the xenograft tumors of B16 and B16F10 mouse melanoma cells implanted in C57BL/6 mice. This evidence concerns the gene CTSG and melanoma.