However, two publications demonstrate that Vdr null mice develop skin tumors after UVB radiation or administration of the chemical carcinogen 7,12 dimethylbenzanthracene (DMBA) but mice lacking Cyp27b1 and so lacking 1,25(OH)2D production do not.(59, 60) That said, discerning mechanisms that are not also influenced by 1,25(OH)2D have not been performed in a consistent fashion. This evidence concerns the gene CYP27B1 and skin neoplasm.