To confirm that BMP and TGF-β activation was present in glioma cells rather than stromal non-neoplastic cells35, we repeated these studies in a glioblastoma possessing an R132H IDH1 mutation, in which glioma cells can be differentiated from non-glioma cells by the presence of the IDH1 R132H mutation. Here, TGFB1 is linked to central nervous system cancer.