IDH1 and glioblastoma: Thus, we divided the MGMT promoter methylation status into 3 levels in the heatmap: “unmethylated,” “weakly methylated,” and “methylated.” The proportion of unmethylated MGMT promoter cases in IDH-mutant GBM was significantly lower (23.9% vs. 64.7%) than that in IDH-wildtype GBM, whereas the proportion of methylated MGMT promoter cases in IDH-mutant GBM (35.8%) was similar to the sum of the proportions of weakly methylated and methylated MGMT promoter cases for IDH-wildtype GBM (35.2%) (Figure 2B).