NSCLC cell lines A549, H1975 and PC9, purchased from The Shanghai Institutes for Biological Sciences of the Chinese Academy of Sciences, were taken out and inoculated to RPMI-1640 culture solution complementary with 10% fetal bovine serum, and cultured at under 37°C with a humidity of 5%CO2 saturation, with liquid exchanging and passaging every 3-4 days.