P46527

p27 Kip1 also known as CDKN1B is a cyclin-dependent kinase inhibitor, which shares a limited similarity with CDK inhibitor CDKN1A/p21. p27 Kip1 plays a crucial role as a negative regulator of cell cycle progression, particularly during the G1 phase, where p27 Kip1 inhibits the activity of cyclin-dependent kinases (Cdks) by binding to D-type cyclins and Cdk4, thereby preventing the transition to the S phase. This regulation is vital for maintaining proper cell growth and division, especially in response to external signals such as transforming growth factor-beta (TGFβ), which can induce G1 arrest. The ability of p27 Kip1 to modulate cell cycle progression highlights its importance in tumor suppression, as dysregulation of p27 Kip1 can lead to uncontrolled cell proliferation and cancer development.