VTCN1 and type 1 diabetes mellitus: Number of preclinical studies support the hypothesis of B7-H4 generating an inhibitory tumor microenviroment, for example, in one study it has been shown that the quantity of B7-H4 on the surface of pancreatic islets cells positively correlates with their resistance to T cell attack in murine models of type 1 diabetes.34 In another study when 4T1 metastatic breast cancer cells were transferred into both wildtype and B7-H4−/− mice.