Pancreatic islet tumors, which are also referred to as pancreatic neuroendocrine tumors (NETs) consist of gastrinomas, insulinomas, pancreatic polypeptidomas (PPomas), glucagonomas, vaso-active intestinal polypeptidomas (VIPomas) and non-functioning tumors and these occur in ∼40% of MEN1 patients; and anterior pituitary tumors, consisting of prolactinomas, somatotrophinomas, corticotrophinomas, and non-functioning adenomas, occur in ∼30% of patients (Benson et al., 1987; Calender et al., 1995; Marx et al., 1998; Trump et al., 1996). This evidence concerns the gene MEN1 and pancreatic neuroendocrine tumor.