AREG is a one-way membrane protein consisting of 252 amino acids. AREG belongs to AREG family and contains an EGF-like domain. AREG is expressed in many tissues, including ovary, placenta, lung, kidney, stomach, colon and breast. It is related to epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha). As an EGF-related growth factor, AREG interacts with EGF/TGF-alpha receptor to promote the growth of normal epithelial cells and inhibit the growth of some invasive cancer cell lines.