TNF and hepatocellular carcinoma: Normoxic regulation of HIF by inflammatory cytokines was firstly described by Hellwig-Burgel et al. [53], where they demonstrated that treatment of human hepatoma (HepG2) cells with TNF-α resulted in elevated HIF-1 activity and HIF-1 DNA binding; however, neither HIF-1α mRNA nor protein levels were reported to be affected by TNF-α, thus implicating a post-translational mechanism [53].