IGF1 and pancreatic neuroendocrine tumor: Although the expression of large T-antigen, as seen in β-cells of Tag transgenic mice, is not known to occur in human islet tumors, Wulbrand and colleagues demonstrated that members of the IGF family and their corresponding receptors and binding proteins are important in carcinogenesis of several tumors, including human pancreatic endocrine tumors [30, 31].