RRM2 and glioblastoma: Whereas 5FU and gemicitabine also inhibit RRM2 (ribonucleoside-diphosphate reductase M2 subunit) and DHFR (dihydrofolate reductase) [29], the new drug raltitrexed may be more specific to TYMS, but no published data are available for glioblastoma treatment.