BTC and cancer: EGFR is overepressed in many cancer types and activated by a variate of ligands [6], including besides EGF also the transforming growth factor-alpha (TGFA), heparin-binding EGF-like growth factor (HBEGF), betacellulin (BTC), amphiregulin (AREG) and epiregulin (EREG) and epigen (EPGN).