RRM2 and glioblastoma: It plays an essential role in regulating the total rate of DNA synthesis.22,23 The gene is implicated in temozolomide therapy resistance and is transcriptionally co-activated by BRCA1, protecting cells from endogenous replication stress, DNA damage, and apoptosis.24–26 Subsequently, in vitro and in vivo studies with inhibition of RRM2 expression showed a significant decrease in tumor growth in various tumors, including GBM, and improved animal survival.27