Conversely, these isoforms are over-expressed in different tumor lines, such as HCT-15 colorectal adenocarcinoma cells, where the increase in the expression of SDHC Δ3 and Δ5 ASVs was found associated with reduced SDH activity and increased production of O2− [23,27]. This evidence concerns the gene SDHC and colorectal adenocarcinoma.