The most common molecular alterations, that characterize glioblastomas and could be used in current clinical practice and therapeutic decision making, are proliferation markers (Ki-67/MIB-1 and phospho-histone-H3 (PHH3)), mutations involving isocitrate dehydrogenase (IDH1 and IDH2) and TP53, also 1p/19q deletion, mutations of Epidermal growth factor receptor (EGFR), O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status and glioma-CpG island methylator phenotype [12-14]. The gene discussed is MGMT; the disease is central nervous system cancer.