Indeed, despite a nearly complete depletion of intracellular 2-HG, no cell growth inhibition has been observed by Tateishi et al. when exposing eight endogenous IDH1-mut cell lines, including six IDH1R132Hmut glioma tumor-initiating cells (TICs), HT1080 (IDH1R132C), and an IDH1R132C-mut melanoma (30T), to the same IDH1 inhibitor (AG-5198) [28] (Table 1). Here, IDH1 is linked to glioma.