In agreement with our initial concept that the biological consequence of IDH mutations is antagonistic toward oncogenic signaling [13], the conclusion of IDH1R132H being intrinsically tumor-suppressive is further supported by the observations that IDH1R132H is anti-tumor growth or incompatible with glioma progression [6, 8–10, 14, 15, 19, 28]. The gene discussed is IDH2; the disease is central nervous system cancer.