EGFR and non-small cell lung carcinoma: In resistant cell lines derived from PC-9 cells (EGFR exon 19del) at clinically relevant concentration of neratinib (HKI-272), an EGFR/pan-HER inhibitor, EGFR T790M gatekeeper mutation was first revealed as an acquired resistance mechanism of NSCLC to second-generation EGFR-TKIs [10].