MGMT and glioblastoma: Genetic mutations in glioblastoma presents genes deletion, encoding cyclin-dependent kinase inhibitors (such as CDK2NA), amplification of epidermal growth factor receptor (EGFR) and cyclin-dependent kinase genes (such as CDK4), and the silencing of the O-6-methylguanine-DNA methyltransferase (MGMT) gene [27].