SYP and neoplasm: In addition, we confirmed by IHC analysis that tumors developed in Men1–/– and hTS/Men1–/– mice were of neuroendocrine origin, since we detected synaptophysin and chromogranin A in tumor tissues (Supplemental Figure 1; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.147417DS1).