FDX2 and hepatocellular carcinoma: Except FDX1, the human genome has another ferredoxin, FDX2. Although both FDX1 and FDX2 participate in the transfer of electrons from nicotinamide adenine dinucleotide phosphate (NADPH) to cytochrome P450 for biogenesis of Fe-S clusters, they have different roles in HCC (47).