Indeed, although there are some controversial data (e.g., CB1 was found to promote growth of human A375 and 501 Mel melanoma cell lines [382]; CB1−/−/CB2−/− double KO mice were protected against DMBA and UVB-treatment induced papilloma formation [87]), majority of the studies agree that cannabinoids deserve further attention as putative future anti-cancer drugs in general [383,384], and in the case of skin tumors as well [100]. Here, CNR1 is linked to papilloma.