Progression through the G1 phase of the cell cycle is regulated in part by the D-type cyclin-dependent kinases, cdk4 and cdk6. p15INK4b is a specific inhibitor of cdk4/cdk6 and is periodically expressed during cell cycle. Induction of p15INK4b is important for TGFß-mediated cytostasis in epithelial cells but not in hematopoietic cells, it may act as an effector of TGF-ß mediated cell arrest.Synonyms: Cyclin-dependent kinase 4 inhibitor B, MTS2, Multiple tumor suppressor 2, p14-INK4b, p14INK4b, p15-INK4b