Effects of Axl and EphA2 knockdown by siRNAs on sensitivities of ADIR cells to EGFRi. (A) and (B) Cell killing assays of five ADIR cell lines treated with lapatinib or gefitinib as indicated; (C) and (D) effects of cell sensitivities to lapatinib or gefitinib, respectively, by Axl-knockdown, respectively; (E) and (F) effects of cell sensitivities to lapatinib or gefitinib, respectively, by EphA2-knockdown cells in ADIR 58R3 and 58R4 cells. * denotes significant (P < 0.05).