Two copies of L858R EGFR hypersensitize A549 cells to EGFR-TKIs.

A. Clonogenic survival assay. Each cell line was plated at 200 cells/well in 6-well plates and incubated in the presence of gefitinib (10 nM) or afatinib (0.3 nM) for 10 days. Colonies were fixed by methanol and stained with crystal violet. B. The number of foci >1 mm was automatically counted using Image J software. Results are the mean cell number relative to control (set to 100%) ± SD (n = 3). Statistical analysis: Bonfferoni correction was used for multiple comparisons. *P<0.05, **P<0.01.