HGF and cancer: TAMs not only provide structural support within the tumor stroma but can also facilitate cancer initiation by secreting signal molecules, including growth factors, such as epithelial growth factor (EGF), platelet-derived growth factor (PDGF), TGF-β, hepatocyte growth factor (HGF), and basic fibroblast growth factor (bFGF) among other cytokines and chemokines [30].