D-2HG and α-KG levels in xenografts. A) D-2HG levels in extracts of xenograft-containing mouse brains from E478 IDH1-mutant and E434 IDH-wild type (wt) tumors as detected by LC-MS. B) In situ detection of D-2HG and α-KG levels in tumor sections using LESA-nano ESI-FTICR. Upper panel shows H&E stained sections of mouse brain (pink) with tumors (blue) from which tissue plugs were analysed. Lower panels show Quantinetix views of tissue plugs for 2-HG (m/z 147.032) and α-KG (m/z 145.017) respectively. C) Quantification of D-2HG and α-KG levels in individual tissue plugs taken from control brain, IDH1-mutant xenografts and IDH-wt xenografts. Sample numbers encircled in blue represent tissue plugs as shown in (B). D) Mean D-2HG and α-KG levels in control brain (ctr B), IDH1-mutant xenografts (m IDH) and IDH-wildtype xenografts (wtIDH). Note the difference in scale of the Y-axes in these graphs. Levels of α-KG were very low as compared to D-2HG levels, but clearly detectable in all plugs.