RRM1 and ependymoma: Notably, ependymomas frequently overexpressed proteins implicated in DNA synthesis, transcription, and repair and/or drug resistance, including BCRP (5/7 [71%]), RRM1 (14/30 [47%]), ERCC1 (13/25 [48%]), TUBB3 (12/21 [57%]), TOPO1 (23/37 [62%]), and MRP1 (8/14 [43%]) [25–30].