Inhibitor of E2F-dependent activation of gene expression. Binds specifically the E2 recognition site without interacting with DP proteins and prevents transcription activation by E2F/DP heterodimers. Controls the timing of endocycle onset and inhibits endoreduplication. Named isoforms=2. Expressed exclusively in mitotically dividing cells. Highly expressed in young leaves and mature flowers. Lower expression in young stalk and in young and mature flowers. Expressed in a cell cycle-dependent manner. Not detected during early S phase. Expressed at both the G1/S and S/G2 transitions, with a peak during G2. No visible phenotype, but increased ploidy levels. Belongs to the E2F/DP family. Truncated N-terminus.