Functional importance of α-KG for histone demethylases and TET family DNA demethylases [43] in epigenetic regulation has been largely demonstrated in human malignancies driven by genetic mutations of IDH1/2 enzymes, which promote overproduction of 2HG – structural analogue but functional inhibitor of α-KG – and lead to profound epigenetic alterations such as aberrant histone and/or DNA hyper-methylations in cancers [27]. Here, IDH1 is linked to cancer.