Supplementary Figure S1: Treatment with octyl-D-2-HG-induces MIR148A methylation; Supplementary Figure S2: Octyl-D-2-HG-induced MIR148A methylation status remains constant at late passages; Supplementary Figure S3: Octyl-D-2-HG induces CpG island methylation of the RBP1 promoter in 293T cells; Supplementary Figure S4: Octyl-D-2-HG induces CpG island methylation of the MIR148A promoter in normal human astrocytes (NHA); Supplementary Figure S5: MIR148A promoter CpG methylation in IDH1MUT-transfected 293T cells; Supplementary Figure S6: C227 prevents IDH1 mutant-induced MIR148A promoter methylation; Supplementary Figure S7: C227 prevents IDH1 mutant-induced RBP1 promoter methylation; Supplementary Figure S8: Schematic graph of MIR148A genomic location, CpG island, and promoter-reporter construct; Supplementary Figure S9: MIR148a expression is unchanged by octyl-D-2-HG treatment in early passages in 293T and NHA cells; Supplementary Figure S10: Octyl-D-2-HG withdrawal restores MIR148A promoter to an unmethylated state