This association has been attributed to the role of the tumor microenvironment, as in vitro studies indicate that several platelet-derived growth factors (PDGF, EGF and serotonin) stimulate the expression of HCC cells and blunt the action of antiangiogenetic drugs such as Sorafenib and Regorafenib [35,36]. This evidence concerns the gene EGF and hepatocellular carcinoma.