In this study, we mechanistically showed that during the cell cycle progression, following the G1/early S-phase-upregulated E2F1, MYBL2 expression was sequentially increased in S-phase and it might continually drive RRM2 transcription by directly binding to the RRM2 promoter in CRC cells (Figs. 3, 4). This evidence concerns the gene RRM2 and colorectal carcinoma.