Confocal immunofluorescent analysis of MCF7 cells using p21 Waf1/Cip1 (12D1) Rabbit mAb (Alexa Fluor® 555 Conjugate) (red) and Phospho-Histone H3 (Ser10) (D2C8) XP® Rabbit mAb (Alexa Fluor® 488 Conjugate) #3465 (green). Blue pseudocolor = DRAQ5® #4084 (fluorescent DNA dye).
This Cell Signaling Technology antibody is conjugated to Alexa Fluor® 555 fluorescent dye and tested in-house for immunofluorescent analysis in human cells. The antibody is expected to exhibit the same species cross-reactivity as the unconjugated p21 Waf1/Cip1 (12D1) Rabbit mAb #2947.
Supplied in PBS (pH 7.2), less than 0.1% sodium azide and 2 mg/ml BSA. Store at 4°C. Do not aliquot the antibody. Protect from light. Do not freeze.
NOTE: Prepare solutions with reverse osmosis deionized (RODI) or equivalent grade water.
NOTE: Cells should be grown, treated, fixed and stained directly in multi-well plates, chamber slides or on coverslips.
Aspirate liquid, then cover cells to a depth of 2–3 mm with 4% formaldehyde diluted in 1X PBS.
NOTE: Formaldehyde is toxic, use only in a fume hood.
NOTE: All subsequent incubations should be carried out at room temperature unless otherwise noted in a humid light-tight box or covered dish/plate to prevent drying and fluorochrome fading.
posted November 2006
revised November 2013
Protocol Id: 182
p21 Waf1/Cip1 (12D1) Rabbit mAb (Alexa Fluor® 555 Conjugate) recognizes endogenous levels of total p21 protein. The antibody does not cross-react with other CDK inhibitors.
Monoclonal antibody is produced by immunizing animals with a synthetic peptide corresponding to residues near the carboxy-terminus of human p21 protein.
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).
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