Betacellulin (BTC) is a member of the EGF family of growth factors that also includes EGF, TGF-α, Amphiregulin, HB-EGF, Epiregulin, Tomoregulin, Heregulin and Neuregulins. Mature human BTC protein exhibits 80% amino acidsimilarity with mouse BTC protein. BTC 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. BTC signals through the EGF receptor.

> 95% as determined by SDS-PAGE; > 95% as determined by HPLC