CDK4 and glioblastoma: In addition, the MDM4 (1q32.1), PDGFRA (4q12), CDK4 (12q14.1), and MDM2 (12q15) genes are also frequently amplified in GBM, whereas inactivation of the NF1 (17q11.2), TP53 (17p13.1) and IDH1/2 (2q34/15q26.1) genes through deletion and/or mutation is also commonly observed [8], [17], [18], [19], [20], [21].