HIF1A and hepatocellular carcinoma: Most in vitro and in vivo HCC models investigating hypoxia-mediated mechanisms in HCC have focused on the upregulation of hypoxia-inducible factor-1α (HIF-1α), a protein that induces the expression of pro-angiogenic factors, including VEGF, platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), and angiopoietin, which can promote HCC angiogenesis in HCC tumours, thus creating a positive pathogenic feedback loop [74–76].