Studies have found that IFN-γ can induce the expression of PD-L1 in A549 lung cancer cells through activating the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling and the phosphatidylinositol 3-kinase (PI3K)/AKT signaling 48. Here, STAT3 is linked to lung cancer.