HGF and neoplasm: CAFs also secrete factors including VEGF, CXCL12, FGF, IL-8/CXCL8 and PDGF to stimulate tumor angiogenesis [37], CAFs release factors such as HGF [34], CCL5 [38] and stanniocalcin 1 (STC1) [39] to stimulate tumor invasiveness and metastasis.