XPC and glioblastoma: This observation, combined with its established role in modulating the base excision repair (BER) pathway through CSB and XPC stabilization in HeLa cells [33–36] and our current data showing similar modulation of XPC in GBM cells (Fig. 4C), indicates that USP7 coordinates the activity of all three major alkylation repair pathways: direct reversal, demethylation, and BER.