Description
Product Usage Information
CST recommends transfection with 100 nM SignalSilence ® p21 Waf1/Cip1 siRNA I 48 hours prior to cell lysis. For transfection procedure, follow protocol provided by the transfection reagent manufacturer. Please feel free to contact CST with any questions on use.
Storage
SignalSilence ® siRNA is supplied in RNAse-free water. Aliquot and store at -20ºC.
Background
The tumor suppressor protein p21 Waf1/Cip1 acts as an inhibitor of cell cycle progression. It functions in stoichiometric relationships forming heterotrimeric complexes with cyclins and cyclin-dependent kinases. In association with CDK2 complexes, it serves to inhibit kinase activity and block progression through G1/S (1). However, p21 may also enhance assembly and activity in complexes of CDK4 or CDK6 and cyclin D (2). The carboxy-terminal region of p21 is sufficient to bind and inhibit PCNA, a subunit of DNA polymerase, and may coordinate DNA replication with cell cycle progression (3). Upon UV damage or during cell cycle stages when cdc2/cyclin B or CDK2/cyclin A are active, p53 is phosphorylated and upregulates p21 transcription via a p53-responsive element (4). Protein levels of p21 are downregulated through ubiquitination and proteasomal degradation (5). RNA interference has been used to silence p21 Cip1 expression in human endothelial cells, preventing TNF-alpha mediated growth inhibition (6).
Alternate Names
CAP20; CDK-interacting protein 1; CDKN1; CDKN1A; CIP1; MDA-6; MDA6; Melanoma differentiation associated protein; Melanoma differentiation associated protein 6; p21; PIC1; SDI1; WAF1
