STAT3 and lung cancer: The expression of PD-L1 on tumor cells might be induced by the secretion of IFNγ via Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) and the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathways, which has been shown in lung cancer [106].