What kind of protein is p21?

cyclin-dependent kinase inhibitor
p21 is a potent cyclin-dependent kinase inhibitor (CKI). The p21 (CIP1/WAF1) protein binds to and inhibits the activity of cyclin-CDK2, -CDK1, and -CDK4/6 complexes, and thus functions as a regulator of cell cycle progression at G1 and S phase.

Is p21 a gene or a protein?

Cell-Cycle Regulators The protein p21 (also known as WAF1, CIP1 or SD11) regulates cell proliferation by inhibiting the cell cycle through the cyclin kinase pathway. It also has been shown to inhibit apoptosis induced by numerous stimuli.

How does p53 upregulate p21?

The CDKN1A gene is transcriptionally activated by p53. Taken together, these elements constitute the p53-p21-RB signaling pathway. Following activation of p53, for example by viral infection or induction of DNA damage, p21 expression is upregulated.

What is p21 controlled by?

p21 is an inhibitor of cyclin-dependent kinase and acts to prevent protein retinoblastoma (pRb) phosphorylation by inhibiting activation of cyclin E/cdk2 complexes that are required for Rb phosphorylation. Expression of p21 is regulated by a number of signaling molecules, including p53 and K-ras.

Is p21 a tumor suppressor protein?

In 1994, p21 (also known as wildtype activating factor-1/cyclin-dependent kinase inhibitory protein-1 or WAF1/CIP1) was introduced as a tumor suppressor in brain, lung, and colon cancer cells; it was shown that p21 induces tumor growth suppression through wild type p53 activity [2].

How is p21-activated?

Abstract The p21-activated kinases (PAKs) 1–3 are serine/threonine protein kinases whose activity is stimulated by the binding of active Rac and Cdc42 GTPases. Our understanding of the regulation and biology of these important signaling proteins has increased tremendously since their discovery in the mid-1990s.

What cancers are associated with p21?

What is the PAK pathway?

PAK is activated through pathways that are important for breast cancer growth. Growth factors such as prolactin and the oncogene human epidermal growth factor receptor 2 (HER2 or ErbB2) can activate MAPK signaling pathway through PAK1.

What is activated kinase?

Summary: The mitogen-activated protein kinases (MAPKs) regulate diverse cellular programs by relaying extracellular signals to intracellular responses. In mammals, there are more than a dozen MAPK enzymes that coordinately regulate cell proliferation, differentiation, motility, and survival.

How is p21 function altered in cancerous cells?

p21 was shown to be responsible for protecting tumor cells from DNA damage cytotoxic effect after Chk1 inhibition. p21 activated kinase (PAK) proteins, have different functions in different species; these proteins are associated with cancer due to their role in cell survival, cell migration, and proliferation [100].

What is Pak protein?

PAK proteins, a family of serine/threonine p21-activated kinases, include PAK1, PAK2, PAK3 and PAK4. These proteins serve as targets for the small GTP binding proteins Cdc42 and Rac and have been implicated in a wide range of biological activities. PAK1 regulates cell motility and morphology.