MEN1 (Menin) is a nuclear protein that functions in histone modification and epigenetic regulation. It is considered a tumor suppressor of some cancer types, and inherited mutations in MEN1 lead to multiple endocrine neoplasia type 1 (MEN-1 syndrome), in which cancers may manifest in the pancreas, parathyroid, pituitary and adrenal gland. Separately, it exhibits oncogenic effects in other cancers such as Ewing sarcoma, where it is overexpressed and epigenetically drives a pro-proliferative transcriptome. Inhibition of MEN1 has been shown to reduce tumor growth in some cases. In immunohistochemistry of normal tissues, MEN1 has low to moderate nuclear positivity in all tissues throughout the body. References: Human Molecular Genetics. 6 (7): 1177–83, PMID: 9215690; Best Pract Res Clin Endocrinol Metab. 2010 Jun;24(3):355-70, PMID: 20833329; J Pathol. 2018 Jul;245(3):324-336, PMID: 29672864