MGMT and glioblastoma: Methylation of the O6-Methylguanine-DNA methyltransferase (MGMT) promoter, which is associated with improved chemotherapy response, is a widely recognized epigenetic determinant in GBM, yet beyond DNA methylation, there is now a greater appreciation for the complex role that histone post-translational modifying enzymes play in regulating GBM pathophysiology (10, 11).