IDH2 and glioblastoma: Besides frequent-occurring mutations in IDH1 and IDH2 and TERT, there are four pathways that are physiologically and pathologically relevant to current glioma/glioblastoma therapies: (1) The P13K-PTEN-AKT-mTOR signaling pathway: In brain cells, this pathway is regulated by the epidermal growth factor (EGF), and its receptor, EGFR, both frequently overexpressed in GBM.