The Activin Receptor is a type of protein found on the surface of cells that plays a crucial role in cellular signaling. It is part of the TGF-β superfamily and is involved in various biological processes, including cell growth, differentiation, and apoptosis. When activated by its ligand, Activin, the receptor initiates a cascade of intracellular signals that influence gene expression. There are two main types of Activin receptors: type I and type II. These receptors work together to form a functional signaling complex. The interaction between Activin and its receptors is essential for regulating processes such as embryonic development, reproductive functions, and tissue repair.