CDK4 and central nervous system cancer: A high frequency of TP53 mutations, CDK4 amplification, or CDKN2A homozygous deletion, and amplifications or rearrangements involving receptor tyrosine kinase and Ras-Raf-MAP kinase pathway genes, including PDGFRA, MET, BRAF, and RRAS2 were found in a study on postradiation glioma to determine the molecular pathogenesis.