A similar role is attributable to ubiquinol–cytochromec reductase hinge (UQCRH), another subunit of complex III that is overexpressed in lung adenocarcinoma47 and in hepatocellular carcinoma.48 UQCRH regulates electron transfer from cytochrome c1 to cytochrome c, and its upregulation results in enhanced ROS production.47 In hepatocellular carcinoma, UQCRH overexpression is accompanied by the upregulation of two other subunits of complex III, the previously described UQCR2 and UQCRB. Here, CYC1 is linked to hepatocellular carcinoma.