While the mechanism of mutation-mediated resistance against target therapy was broadly investigated in lung cancer and others such as breast cancer and colon carcinoma and a great progress had been made, the other consequences of typical mutation in EGFR such as T790M, L858R, and T790M/L858R, why new resistance develops during target therapy, and how cancer cells escaped from KTI remain largely unclear. This evidence concerns the gene EGFR and lung cancer.