p21 (WAF1, Cip1) Polyclonal Antibody, eBioscience™, Invitrogen™

Description

• Description: The polyclonal antibody reacts with mouse, rat, and human p21; the antibody was raised against a peptide mapping to the carboxy terminus of human p21
• The progression through the cell cycle is regulated by cyclins and their cognate Cdks by promoting cell cycle transitions (1,2,3)
• This orderly progression can be inhibited by a family of proteins known as CDK inhibitors (CDIs) that bind to cyclin/Cdk complexes and halt cell division (3)
• p21 (also designated WAF1/Cip1) is one has been shown to inhibit the activity of each member of the cyclin/Cdk family and over expression of this protein inhibits the proliferation of mammalian cells (5)
• The expression of p21 is inducible by a wide range of stress stimuli and its transcription can be enhanced by p53 (6)
• Another member of the CDIs is p27 (also known as Kip1), which also sees up regulation in response to antimitogenic stimuli (7)
• The increased protein expression of p27 results in cellular arrest by binding to cyclin/Cdk complexes, like cyclin D1/Cdk4 (4,8)
• An additional CDI has been found to bind Cdk4 and Cdk6, p16 (INK4A), and when such complexes are formed, the progression of the cell cycle is halted (9)
• It has become increasingly clear that p16 is a very important tumor suppressor gene whose frequent loss occurs early in many human cancers
• p16 is a major target in carcinogenesis that is rivaled in frequency only by p53 (10)
• Protein p21 is a tumor suppressor protein which is an inhibitor of Cyclin-dependent kinases (CDK) and is transcriptionally activated by p53
• P21 is important in the response of cells to genotoxic stress and a major transcriptional target of p53 protein
• The occurrence of p21 in the nucleus executes binding and inhibition activity of cyclin dependent kinases Cdk1 and Cdk2, and blocks the transition from G1 phase into S phase or from G2 phase into mitosis after DNA damage, which enables the repair of damaged DNA
• In the cytoplasm, p21 protein has an anti-apoptotic effect
• P21 is able to bind to and inhibit caspase 3, as well as the apoptotic kinases ASK1 and JNK
• P21 exhibits a dual function in carcinogenesis, and acts as a tumor suppressor, prevents apoptosis, and acts as an oncogene.