In a study of 28 subjects with MEN-1, 100 PETs were detected, among which 77 tumors were positive for the following hormones: 37 - glucagon, 27 - insulin, 11 - PP, 1 - gastrin, 1 - VIP, and 7 - unclassified, however this study represents unusual statistics compared to the other studies [35]. This evidence concerns the gene PPY and multiple endocrine neoplasia type 1.