Reduced PPARγ activity is noted in mice susceptible to skin cancer induced by dimethylbenz[a]anthracene [7], but activation of PPARγ with rosiglitazone treatment does not prevent the development of skin tumors induced by ultraviolet light or chemical such as dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol-13-acetate in mice [8]. This evidence concerns the gene PPARG and skin neoplasm.