XRCC6P5 and glioblastoma: A notable feature of treatment-resistant GBM is the enzyme O6-methylguanin-DNA methyltransferase (MGMT), a DNA-repair protein that removes the alkyl group from the O6 position of alkyl groups, and consequently diminish the curative effects of chemotherapeutic agents [25], conversely, the silencing of MGMT through promoter methylation is associated with prolonged OS and disease-free survival (DFS) in patients with GBM [26].