MRC1 and glioblastoma: One major mechanism that leads to TMZ resistance in GBM is the absence of the MMR system and MLH1 deficiency can confer GBM TMZ resistance.[17] ChIP‐qPCR assay results revealed no markedly difference of H3K9la in the MLH1 promoter in the TMZ‐resistant cells compared to parental cells (Figure S6B, Supporting Information).