We found that in AhR+/+ mice, BaP induced lung cancer (Fig. 3h); but in AhR-/- mice, BaP-induced lung cancer was inhibited (Fig. 3h, i), life span was prolonged (Fig. 3j), and PD-L1 upregulation was markedly attenuated (Fig. 3k, l). This evidence concerns the gene AHR and lung cancer.