Figure 3A shows that incubation of lung cancer cells in hypoxic environment markedly increased the expressions of HIF-1α and PD-LI, suggesting that the expression of PD-L1 is related to that of HIF-1α. Figure 3B demonstrates that the expressions of HIF-1α and PD-L1 in FSaII tumor cells in vitro increased under chemically induced hypoxia (CoCl2), and knockdown of HIF-1α with siRNA markedly reduced the expression of PD-L1. This evidence concerns the gene HIF1A and lung cancer.