The promoter of the CDC25C gene contains p53 response elements as well as E2F binding sites and can bind both TP53 (St Clair et al. 2004) and E2F4 (Benson et al. 2014). E2F4 transcription repressor complex consists of E2F4, a transcriptional co-factor TFDP1 (DP1) or TFDP2 (DP2), and a retinoblastoma family protein RBL1 (p107) or RBL2 (p130). The CDK inhibitor p21 (CDKN1A), induced by TP53, positively affects E2F4 recruitment to the CDC25C promoter, probably by upregulating RBL2 (Helmbold et al. 2009, Benson et al. 2014).