RXRαep−/−|Tyr-NRASQ61K| Cdk4R24C/R24C melanocytic tumors displayed an increase in the number of cells that stained positive for melanoma antibody cocktail HMB45 and MART-1, which correlated well with the higher VGP in those mice, and a similar increase in CD31 staining implies that the larger melanocytic tumors formed in those mice would necessitate additional vascularization for nutritional support. This evidence concerns the gene PECAM1 and melanoma.