Transcription activator that binds DNA cooperatively with DP proteins through the E2 recognition site, 5'-TTTC[CG]CGC-3' found in the promoter region of a number of genes whose products are involved in cell cycle regulation or in DNA replication. The binding of retinoblastoma-related proteins represses transactivation. Involved in the control of cell-cycle progression from G1 to S phase and from G2 to M phase. Stimulates cell proliferation and delays differentiation. Represses cell enlargement and endoreduplication in auxin-free conditions. Heterodimer with DP proteins. Interacts (via dimerization domain) preferentially with DPA, but also with DPB. Interacts with PURA1 and retinoblastoma-related protein RBR1. Component of a DREAM-like complex which modulates a variety of developmentally regulated genes and of the mitotic genes in proliferating and differentiated cells. Interacts with MYB3R4 only at early stages of leaves development (PubMed:26069325). Interaction with DPA induces an exclusive nuclear localization, but an interaction with DPB has no effect. Expressed in proliferating cells and several differentiated tissues. Detected in inflorescence and shoot apical meristems, cotyledonary vascular tissues, leaf primordia, young leaves, base of trichomes, central cylinder and elongation zone of roots, lateral root primordia, flowers, pistils of immature flowers and pollen grains. Expressed in a cell cycle-dependent manner. Most abundant at the G1/S transition. Lower but constant level in the following phases. Up-regulated by light and by auxin. May be up-regulated by E2FA. Phosphorylated. Belongs to the E2F/DP family.