MSMB is a member of the immunoglobulin binding factor family that is synthesized by the epithelial cells of the prostate gland and secreted into the seminal plasma. It has inhibin-like activity and may function as an autocrine paracrine factor in uterine, breast and other female reproductive tissues. MSMB expression has been found to be decreased in prostate cancer. In immunohistochemistry, MSMB has cytoplasmic positivity in the stomach, prostate, lungs, liver, kidney, pancreas, breast, gastrointestinal tissue, fallopian tubes and the testes. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804;