However, the combination effect of radiation and TMZ on GBM treatment varies, depending on the presence or absence of O6-methylguanine-DNA methyltransferase (MGMT) expression, which is regulated by MGMT promoter methylation status5,6, a known potential predictor of GBM treatment response to TMZ and a major determinant of a patient’s prognosis6. Here, MGMT is linked to glioblastoma.