p27 is an important regulator of cell cycle progression, involved in G1 arrest. It is a potent inhibitor of cyclin E1- and cyclin A-CDK2 complexes and a positive regulator of cyclin D-dependent kinases such as CDK4. The degradation of this protein, which is triggered by its CDK-dependent phosphorylation and subsequent ubiquitination by SCF complexes, is required for the cellular transition from quiescence to the proliferative state. Decreased levels of p27 are found in various epithelial tumours originating from lung, breast, colon, ovary, oesophagus, thyroid and prostate. Defects in the gene encoding p27 (CDKN1B) are the cause of multiple endocrine neoplasia type 4 (MEN4) an inherited cancer of the thyroid.

For Specific Activity data, refer to the Certificate of Analysis for individual lots of this enzyme.

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