Activin B is a protein that belongs to the transforming growth factor-beta (TGF-β) superfamily. It plays a crucial role in various biological processes, including cell growth, differentiation, and regulation of the immune system. Activin B is primarily produced in the ovaries, but it is also found in other tissues throughout the body. This protein functions by binding to specific receptors on cell surfaces, initiating signaling pathways that influence gene expression. Research has shown that Activin B is involved in reproductive health, inflammation, and tissue repair, making it a significant focus in studies related to developmental biology and disease.