To elucidate potential mechanisms of intrinsic resistance to EGFR-TKIs, we evaluated response heterogeneity to EGFR-TKIs in seven NSCLC cell lines (PC-9, HCC827, HCC2935, HCC4006, H1650, HCC2279, H1975) by exposing these cells to a series of concentrations of gefitinib or osimertinib. This evidence concerns the gene EGFR and non-small cell lung carcinoma.