Although BT142 has limited 2HG production (Fig. 1D), we found that the transcriptome of BT142 is most similar to our heterozygous IDH1 MT cell line HK252 and still distinct from IDH1 WT cell lines (Supplementary Fig. 1A), indicating that even with the loss of 2HG production, the line possesses many of the essential features of IDH1 mutant gliomas. This evidence concerns the gene IDH1 and central nervous system cancer.