Thus, amplification of DNA sequences at the 12q13-14 chromosomal region usually included the CDK4 gene together with the METTL1, CYP27B1, AVIL, CTDSP2, METT21B, AGAP2 and OS9 genes, while genetic amplification at 12q15 affected the MDM2 oncogene in a significant fraction of all (primary) GBM tumors analyzed. Here, CDK4 is linked to glioblastoma.