On this basis, four subgroups of adult glioblastoma have been identified, including an IDH mutant, and three IDH wild-type glioblastoma subgroups; the IDH mutant subtype has methylated O6-methylguanine methyltransferase (MGMT) promoter, displays a number of chromosomic aberrations and other alterations such as MYC activation, upregulation of the receptor tyrosine kinase (RTK)/Ras/PI3K pathway and mutations of genes encoding inhibitors of the G1/S cell-cycle checkpoint, including the Rb pathway [10,11]. This evidence concerns the gene RB1 and glioblastoma.