Based on a previous study, where the gene expression of mutated IDH1 caused an elevated radiosensitivity and a reduced aggressive biological behavior of different malignant glioma cell lines, this study dissects molecular mechanisms, underlying the influence of the most frequent IDH mutation (IDH1R132H) in the investigated transduced malignant glioma cells [41]. The gene discussed is IDH2; the disease is malignant glioma.