HGF and neoplasm: Many studies have shown that TAMs can express a variety of cytokines that stimulate tumor cell proliferation and survival, including epithelial growth factor (EGF), platelet-derived growth factor (PDGF), TGF-β1, hepatocyte growth factor (HGF), and epithelial growth ligands of the factor receptor (EGFR) family and basic fibroblast growth factor (BFGF) (25).