Fig. 7.

H3K27 methylation profile in KARPAS-422 cells and Pfeiffer EZH2 mutant xenografts. Extracted ion chromatogram (A) of 14 different methylated forms (B) of the H3 27-40 peptide from KARPAS-422 cells (2+ and 3+ precursors, supplemental Table S4). Identification of each respective isoform is based on inspection of individual tandem mass spectra (supplemental Fig. S7), allowing us to differentiate the various methylated forms of H3K27 and H3K36. C, monitoring these different extracted ion chromatograms allows accurate relative quantitation of the methyl status on H3K27 from Pfeiffer EZH2 mutant xenografts before and after treatment with the EZH2 inhibitor tazemetostat (57). Error bars represent the standard error of two (vehicle) or three (drug treatment) biological replicates.