BACKGROUND p21WAF1/Cip1 belongs to the Cip/Kip family of cyclinkinase inhibitors (CKI) (p21Waf1/Cip1, p27Kip1, p57Kip1). p21Waf1/Cip1 was first described as a potent and universal inhibitor of cyclin-dependent kinases (Cdks). Two forms of functionally active p21 has been localized and described: a nuclear and acytoplasmic forms. p21 functions as a checkpoint in the cell cycle by inhibiting cdks at the G1/S and G2/M interfaces.1 p21 has been shown to bind to cyclin-cdk complexes, preventing phosphorylation of the retinoblastoma protein. When this happens, the E2F pathway is blocked and the cell cycle is arrested at the G1/S interface.
p21 expression is usually controlled at the transcriptional level by either the p53-dependent or -independent pathway,2 but p21 expression can also be regulated at the post-transcriptional level. Short wavelength UVC was found to induce p21 in a p53-dependent fashion by post-transcriptional modifications that led to enhanced stability of p21 mRNA.3 The transcription factors C/EBPa and C/EBPb were found to interact with p21 protein and protect it from proteolytic degradation. In a number of other cell lines, post-transcriptional events strongly influence p21 expression following genotoxic stress. Stress activated kinases p38alpha and JNK 1 were shown to stabilize p21 by phosphorylation at serine 130. p21 was shown to promote apoptosis, protect cells from undergoing apoptosis, inhibit or promote differentiation.4
REFERENCES
1. Harper, J.W. et al: Cell 75:805-816, 1993 2. Blundell, R.A.:Am. J. Biochem. Biotech. 2:33-40, 2006 3. Wang, W. et al: Mol. Cell. Biol. 20:760-771, 2000 4. Cox, L. S.: J. Path. 183:134-140, 1999
Products are for research use only. They are not intended for human, animal, or diagnostic applications.
Cat.No.: | CG1650 |
Antigen: | Peptide sequence around aa. 143-147 (R-Q-T-S-M), according to the protein CDKN1A. |
Isotype: | Rabbit IgG |
Species & predicted species cross- reactivity ( ): | Human |
Applications & Suggested starting dilutions:* | WB 1:500-1:1000 IP n/d IHC n/d ICC n/d FACS n/d |
Predicted Molecular Weight of protein: | 21 kDa |
Specificity/Sensitivity: | Detects endogenous p21 WAF1/Cip1 proteins without cross-reactivity with other family members. |
Storage: | Store at -20°C, 4°C for frequent use. Avoid repeated freeze-thaw cycles. |
*Optimal working dilutions must be determined by end user.