MEN1 is a tumor suppressor gene associated with multiple endocrine neoplasia type 1 and many sporadic endocrine tumors, such as parathyroid tumors, pancreatic insulinomas, and pituitary adenomas, suggesting somatic MEN1 mutations play a role in nonhereditary endocrine tumors (9-12). This evidence concerns the gene MEN1 and pancreatic insulinoma.