RRM2 and cancer: Among the E2F-dependent target genes, FOXM1, a member of the Forkhead superfamily of transcription factors, regulates target genes implicated in cancer initiation, progression, or drug resistance, such as RRM2, BIRC5, CCNB1, PLK1, BUB1B, CENPA, KIF20A, TOP2A, BRCA2, CHEK1, and RAD51 [15,46].