EGFR and lung cancer: Whether HER2, HER3, and Axl are involved in the enhanced autophosphorylation of EGFR mutants, such as T790M/L858R and T790M/C797S/L858R in lung cancer cells, relevant siRNAs will be used to downregulate their expression and then re-expression of wild-type or mutant EGFR-GFP, respectively or the co-expression of wild-type and mutant EGFR-GFP.