In conventional IDH-wildtype glioblastomas, cell cycle dysregulation is most frequently achieved through CDKN2A/B homozygous deletion, CDK4 amplification, or RB1 mutation/deletion, which were present in 70% (316/450), 16% (71/450), and 12% (56/450) of our conventional glioblastoma cohort, respectively. Here, RB1 is linked to glioblastoma.