MGMT and glioblastoma: Thus, complex genetic alterations and genomic profiles (which usually involve multiple signalling pathways) have been defined for GBM; they include copy number variations (chr 7 gain, chr 10 and chr 9p losses), gene mutations and alterations (in PTEN, TP53, EGFR, and PIK3CA), gene amplifications or deletions (EGFR, MDM2, PDGFRA, and CDKN2A/B) and promoter methylation (in MGMT) [4, 5].