HIF1A and cancer: This mechanism deviates from the HIF activated Warburg effect seen in many cancer phenotypes43,45–47, where a causal link between inactivation of FH and/or loss of FH enzyme leads to accumulation of succinate and fumarate, which subsequently leaves the mitochondria and inhibits prolyl hydroxylase in the cytosol, thereby inhibiting the HIF1-α hydroxylation43.