Serine/threonine-protein kinase involved in the control of the cell cycle and differentiation; promotes G1/S transition. Phosphorylates pRB/RB1 and NPM1. Interacts with D-type G1 cyclins during interphase at G1 to form a pRB/RB1 kinase and controls the entrance into the cell cycle. Involved in initiation and maintenance of cell cycle exit during cell differentiation; prevents cell proliferation and regulates negatively cell differentiation, but is required for the proliferation of specific cell types (e.g. erythroid and hematopoietic cells). Essential for cell proliferation within the dentate gyrus of the hippocampus and the subventricular zone of the lateral ventricles. Required during thymocyte development. Promotes the production of newborn neurons, probably by modulating G1 length. Promotes, at least in astrocytes, changes in patterns of gene expression, changes in the actin cytoskeleton including loss of stress fibers, and enhanced motility during cell differentiation. Prevents myeloid differentiation by interfering with RUNX1 and reducing its transcription transactivation activity, but promotes proliferation of normal myeloid progenitors. Delays senescence. Promotes the proliferation of beta-cells in pancreatic islets of Langerhans (By similarity). May play a role in the centrosome organization during the cell cycle phases. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by Thr-177 phosphorylation and Tyr-24 dephosphorylation (By similarity). Rapidly down-regulated prior to cell differentiation (e.g. erythroid and osteoblast) (By similarity). Interaction with D-type G1 cyclins. Cyclin binding promotes enzyme activation by phosphorylation at Thr-177 (By similarity). Binds to RUNX1, CDKN2D, FBXO7 and CDKN2C/p18-INK4c. Forms a cytoplasmic complex with Hsp90/HSP90AB1 and CDC37. FBXO7-binding promotes D-type cyclin binding (By similarity). Localized to the ruffling edge of spreading fibroblasts. Kinase activity only in nucleus (By similarity). Present in the cytosol and in the nucleus in interphase cells and at the centrosome during mitosis from prophase to telophase (By similarity). Localized to the cytosol of neurons and showed prominent staining around either side of the nucleus. Expressed in subgranular zone (SGZ) of the hippocampal dentate gyrus (DG) and the subventricular zone (SVZ) of the lateral ventricles whose neural precursor cells (NPC) give rise to dentate granule neurons and olfactory bulb (OB) interneurons, respectively. Expressed in the neuroepithelium of the cerebral cortex of the developing brain. Thr-177 phosphorylation and Tyr-24 dephosphorylation promotes kinase activity. Slight anemia and defective proliferation of some hematopoietic cells, thymocytes and progenitor cells. Females are reduced in size and often sterile. Prevents the expansion of neuronally committed precursors by prematurely exiting the cell cycle and lengthening G1 phase duration, reducing concomitantly the production of newborn neurons. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. CDC2/CDKX subfamily.