Signal transducer and activator of transcription 3 (STAT3) is an important mediator of the interleukin-6 (IL-6)/Janus tyrosine kinase (JAK)/STAT3 signaling pathway and has been shown to promote tumorigenesis in various cancers, including lung cancer, lymphoma, pancreatic cancer and hepatocellular carcinoma [8,9]. Here, STAT3 is linked to lung cancer.