IDH2 and glioblastoma: Following two-step DGU, nanotracker analysis to determine size and concentration was also performed on exosomes isolated from glioma tumors that were grade 2, 3, or GBM grade 4 (Figures 3A,B), new or recurrent (Figures 3C,D), and IDH WT or mutant (Figures 3E,F).