Probetacellulin can be cleaved into the Betacellulin (BTC) that is a single-pass type I membrane protein containing 1 EGF-like domain. Predominantly expressed in pancreas and small intestine,Betacellulin (BTC) is synthesized primarily as a transmembrane precursor, which is then processed to mature molecule by proteolytic events. As a potent mitogen for retinal pigment epithelial cells and vascular smooth muscle cells, Betacellulin (BTC) is also the growth factor that binds to EGFR, ERBB4 and other EGF receptor family members. Betacellulin (BTC) was originally identified as a growth-promoting factor in mouse pancreatic β-cell carcinoma cell line and has since been identified in humans. The amino acid sequence of mature mBTC is 82.5%, identical with that of human BTC (hBTC), and both exhibit significant overall similarity with other members of the EGF family.