MGMT and cancer: Although considerable attention has been focused on several key molecular events, such as expression of O6-methylguanine-DNA methyltransferase (MGMT), mutations in IDH, ATRX and EGFR gene, other mechanisms, such as cancer stem-like cells, Poly(ADP)-ribose polymerase, are also associated with TMZ resistance in GBMs (14–17), suggesting the complexity of the mechanism underlying TMZ resistance.