STAT3 and cancer: The representative tumor-intrinsic signals include AKT serine/threonine kinase 1 (AKT)-mammalian target of rapamycin signaling, MYC protooncogene, Signal transducer and activator of transcription 3 (STAT3), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), which have been observed in various cancer types [51].