Glioblastoma (GBM), the most frequent malignant brain tumor in adults, is a devastating disease with a median survival of 14.6 months for patients treated with standard radiotherapy and chemotherapy and reaching a median of 21.7 months when selecting patients whose tumors have epigenetic silencing of the O6-methylguanine-DNA methyltransferase (MGMT) DNA repair gene by promoter methylation (1). The gene discussed is MGMT; the disease is glioblastoma.