Interacts strongly with CDK4 and CDK6. Potent inhibitor. Potential effector of TGF-beta induced cell cycle arrest (By similarity). Heterodimer of CDKN2B with CDK4 or CDK6. Expression abundant in lung, less abundant in testis, barely detectable in liver, and not detectable in neonatal kidney, adult kidney, brain, heart, or spleen. Belongs to the CDKN2 cyclin-dependent kinase inhibitor family.