EGFR and cancer: Furthermore, ligand dose-response curves were similar in cells stimulated acutely (10 min) with EGF and transforming growth factor alpha (TGFα), an EGFR ligand that is frequently produced by cancer cells (Grandis and Tweardy, 1993) but is more readily dissociated from the receptor in the acidic environment of endosomes when compared with the canonical ligand, EGF (Roepstorff et al., 2009) (data not shown).