IDH1 and glioblastoma: Consistent with this postulate are our findings that IDH1-mutated glioblastomas and our engineered IDH1-mutated glioblastoma cells displayed lower levels of Mcl-1 and treatment with a cell-permeable form of 2-HG (pharmacologically relevant concentrations) suppressed Mcl-1 protein levels in IDH1 wild-type cells.