ERBB3 and non-small cell lung carcinoma: Overexpression of heregulin makes EGFRM+ NSCLC cell lines resistant to erlotinib via sustained activation of the by-pass ERBB3-AKT signaling pathway and the growth of these cells can be inhibited by the pan-ERBB inhibitor afatinib or by combining erlotinib with the anti-ERBB3 monoclonal antibody patritumab [168,169].