VHL and hepatocellular carcinoma: Previous studies performed with HIF-1α deficient HCT 116 human colorectal and murine hepatoma HEPA-1 cancer cells [14], as well as with VHL modified human clear cell renal cell carcinoma cells with HIF-1α, HIF-2α and combined HIF-1α and HIF-2α downregulation [13] have provided a wealth of information on the effects of HIF downregulation on cell metabolism.