EGFR and lung cancer: In cell line models with the highest sensitivities to EGFR TKIs, the vast majority of EGFR-mutated lung cancer cells are killed within a few days upon exposure to a clinically relevant concentration of an EGFR TKI, whereas a small fraction of viable, largely quiescent cells (≈0.3%) remains detectable after several days in the presence of an EGFR TKI [21].