EGFR and non-small cell lung carcinoma: To investigate the molecular mechanism of EGFR-TKIs resistance, we primarily evaluated the effects of gefitinib and osimertinib, the first and third generation of EGFR-TKIs, respectively, on growth of EGFR-mutant NSCLC cell lines after 72 h of treatment (PC9, PC9-gef, HCC827, HCC827-gef, HCC827-osi) (Fig. 1a).