SDHB and neoplasm: In two distinct data sets, we observed that in HCC liver samples the expression of PDHA1 gene, which encodes the E1 alpha 1 subunit of the PDH complex, was significantly higher than that in non-tumor tissue (P < 0.0001) or normal livers (P < 0.0001), while in HCC samples the expression of the succinate dehydrogenase (SDHB), which converts succinate into fumarate in the TCA, was significantly lower than that in non-tumor tissue (P < 0.0001) or normal livers (P < 0.0001) (Figures 3A,B).