MGMT and glioblastoma: Cox univariate analyses, which yield a hazard ratio (HR) that determines chance of death (HR > 1 indicates high risk of death), showed that Cx43-high patients displayed high risk of death in the group of All GBM, MGMT–, and Recurrent GBM (Fig. 2B), but not in the group of primary or MGMT + GBM (Supplemental Fig. S4B).