MDM4 and glioblastoma: As shown in Figure 4(b), these nine clusters contain nine previously identified GBM related genes [34], including EGFR, MDM2, PDFGFA, MDM4, CDK4, MET (amplifications), CDKN2A, PTEN, and RB1 (deletions); however, MDM4 and RB1 lie slightly out of the detected region.