Betacellulin （BTC） is a member of the epidermal growth factor （EGF） family. Betacelluli is expressed in most tissues including kidney, uterus, liver and pancreas. It is also present in body fluids, including serum, milk, and colostrum. It is synthesized primarily as a transmembrane precursor, which is then processed to a mature molecule by proteolytic events. Betacellulin signals through the EGF receptor.