Cellular functions of menin.

Since its discovery as a novel protein some 10 years ago, many cellular functions of menin have been identified. However, which ones of these relate specifically to menin's role as a tumor suppressor and which ones not remains unclear. Menin is predominantly nuclear and acts as a scaffold protein to regulate gene transcription by coordinating chromatin remodeling. It is implicated in both histone deacetylase and histone methyltransferase activity and, via the latter, regulates the expression of cell cycle kinase inhibitor and homeobox domain genes. TGF-beta family members are key cytostatic molecules and menin is a facilitator of the transcriptional activity of their signaling molecules, the Smads, thereby ensuring appropriate control of cell proliferation and differentiation.