HGF and cancer: The main function of cancer-associated fibroblasts (CAFs) main function has been shown to be in preserving the microenvironment for tumor cell growth and proliferation via the secretion of a large variety of autocrine and paracrine cytokines and other tumor-promoting factors such as CCL5, CCL7, CXCL12, CXCL14, epidermal growth factor (EGF), hepatocyte growth factor (HGF), IL-6, IL-17, and VEGF (61, 345–348) (Figure 4).