IDH1 and glioblastoma: GBM cells carrying the R132H-IDH1 are specifically resistant to histone deacetylase inhibitors (HDACi), such as trichostatin A, vorinostat and valproic acid as a consequence of the 2-HG-induced transcriptional increase of NANOG [66], a key regulator of stemness and self-renewal properties of cancer cells.