E2F-DP transcription factors are activated by phosphorylation of RBR proteins by cyclin D complexes. E2F proteins modulate expression of target genes by binding to cis-acting elements in their promoter. E2F3-DP complex modulate the expression of genes involved in DNA replication at the G1-to-S transition phase (Vandepoele et al., 2005; de Veylder et al., 2007).