STAT3 and cancer: The key signaling pathways of the IL-6/JAK/STAT3 axis promote tumor growth, metastasis, and metabolism (35), IL-6 also activates the Yes-associated protein (YAP) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) signaling pathways to promote cell proliferation, migration and invasion as well as mediating activation of transcription factors CCAAT/enhancer-binding protein beta/delta (C/EBPβ/δ) to induce epithelial-mesenchymal transition (EMT) and amplification of cancer stem cells (36, 37).