p27/Kip1 [DCS-72.F6]

p27Kip1 is a cyclin-dependent kinase inhibitor involved in G1 arrest. p27Kip1 binds to and inhibits cyclinE-Cdk2 complex, cyclinA-CDK2 and cyclinD1-CDK4 (1). p27Kip1 is regulated by phosphorylation on serine 10 (S10) and threonine 187 (T187). Phosphorylation by CDK2 on T187 results in ubiquitination and degradation of p27Kip1, while phosphorylation by hKIS on S10 signals nuclear export to the cytoplasm. The expression level of p27Kip1 is high in normal cells. Downregulation of p27Kip1 is found in many types of cancers, and decreased expression of p27Kip1 appears to be a poor prognostic factor in several tumor models, including carcinomas of the lung, breast, colorectal, and prostate.