VEGFA and hepatocellular carcinoma: The Ras-RAF-ERK-dependent pathway is implicated in the molecular pathogenesis of HCC for three reasons: i) Ras protein is activated in the 30% of cases of HCC [77]; ii) the over-expression of Raf kinase is in the majority of HCC [78]; iii) several upstream growth factors, such as EGF, VEGF, PDGF, TGFα, generally over-expressed in HCC, can activate this pathway binding proper tyrosin kinase receptors [79].