Several TFs have been identified for regulating RRM2 transcription in different cancers, such as E2F1 in CRC [20], BRCA1 and E2F1 in glioblastoma [19], HPVE7 in cervical cancer [26], and FOXM1 in prostate cancer [18], and etc. [27, 28]. Here, E2F1 is linked to cancer.