Afatinib, also known as BIW-2992, is an irreversible dual inhibitor of epidermal growth factor receptor 1 (EGFR) and 2 (HER2) tyrosine kinases. Afatinib suppresses EGF-induced EGFR phosphorylation and cellular proliferation in various cell lines, including EGFR-overexpressing and HER2-expressing cell lines A431, NIH-3T3-HER2, NCI-N87 and BT-474.