HGF and neoplasm: Several tumor-cell-derived growth factors, such as transforming growth factor β (TGF-β), hepatocyte growth factor (HGF), epidermal growth factor (EGF), fibroblast growth factor (FGF), Wnt ligand, interleukin-6 (IL-6), and hedgehogs act as extracellular EMT inducers and activate downstream signaling, including the TGF-β/SMAD, PI3K/ protein kinase B (AKT), mitogen-activated protein kinases (MAPKs), and Wnt/β-catenin signaling pathways [5].