MGMT and neoplasm: The pathogenesis of GRE involves many factors including tumor histology, tumor location, microenvironment; specific genetic alterations such as isocitrate dehydrogenase 1 (IDH1) gene mutation, O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation; aberrant expression of potassium chloride cotransporter (KCC2), solute carrier family 7 member 11 (SLC7A11), glutamate, etc (8–11).