CDKN2A and glioma: The molecular progression of gliomas, like many tumors, involves the accumulation of genetic and epigenetic alterations that result in the loss of tumor suppressor gene function (PTEN, TP53, CDKN2A, RB) or the activation of oncogenic pathways (p21–RAS, PI3K, EGFR, CDK4, MDM2) [6–8].