IDH2 and cancer: The mechanistic role of IDH in these cancers has been determined by analysing point mutations at specific arginine residues (residues R132 and R172/R140 in IDH1 and IDH2, respectively — Figure 2b) that disrupt catalytic activity, resulting in neomorphic enzymatic activity, and the subsequent accumulation of 2-hydroxyglutarate (D-2HG) from the reduction of a-KG.