RB1 and glioma: In gliomas, compared with normal brain tissue, promoter hypermethylation of the RB, CDKN2A, PTEN and P53 genes has been clearly identified, and these changes serve as prognostic predictors.27 The other well-known mechanism is the methylation of the MGMT promoter, which leads to MGMT-dependent TMZ resistance and recurrence.32 These findings indicate that DNA methylation actively participates in regulating glioma progression.