Regulator of biological processes that recruits a histone deacetylase to control gene transcription. Formation of stable complexes with geminiviridae replication-associated proteins may create a cellular environment which favors viral DNA replication (By similarity). May play a role in the entry into mitosis, negatively regulating the cell proliferation during leaf, stem, and flower development. Critical regulator of the endocycle. Expressed in roots, stems, leaves and flowers. Plants undergoing virus-induced gene silencing (VIGS) exhibit clusters of undifferentiated cells around mature stomata, indicating uncontrolled cell division from meristemoids, as well as increased ploidy level in some cells. Belongs to the retinoblastoma protein (RB) family.