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  • KD/KO Validated

P21 Polyclonal antibody

P21 Polyclonal Antibody for WB, IP, IF, FC, IHC, ELISA

Host / Isotype

Rabbit / IgG


human and More (4)





Cat no : 10355-1-AP


CAP20, CDK interacting protein 1, CDKN1, CDKN1A, CIP1, MDA 6, MDA6, P21, p21CIP1, PIC1, SDI1, WAF1

Tested Applications

Positive WB detected inHUVEC cells, MCF-7 cells, HeLa cells, HEK-293 cells, HepG2 cells, THP-1 cells, LNCaP cells, NCCIT cells, U2OS cells
Positive IP detected inMCF-7 cells
Positive IHC detected inhuman cervical cancer tissue, human breast cancer tissue, human colon cancer tissue, human thyroid cancer tissue, human stomach cancer tissue, human kidney tissue
Note: suggested antigen retrieval with TE buffer pH 9.0; (*) Alternatively, antigen retrieval may be performed with citrate buffer pH 6.0
Positive IF detected inMCF-7 cells, myotome of a somite at E11.5 tissue
Positive FC detected inMCF-7 cells

Recommended dilution

Western Blot (WB)WB : 1:1000-1:4000
Immunoprecipitation (IP)IP : 0.5-4.0 ug for 1.0-3.0 mg of total protein lysate
Immunohistochemistry (IHC)IHC : 1:200-1:600
Immunofluorescence (IF)IF : 1:50-1:500
Flow Cytometry (FC)FC : 0.40 ug per 10^6 cells in a 100 µl suspension
It is recommended that this reagent should be titrated in each testing system to obtain optimal results.
Sample-dependent, Check data in validation data gallery.

Product Information

10355-1-AP targets P21 in WB, IP, IF, FC, IHC, CoIP, ELISA applications and shows reactivity with human samples.

Tested Reactivity human
Cited Reactivityhuman, rabbit, pig, Artemia sinica, canine
Host / Isotype Rabbit / IgG
Class Polyclonal
Type Antibody
Immunogen P21 fusion protein Ag0368
Full Name cyclin-dependent kinase inhibitor 1A (p21, Cip1)
Calculated Molecular Weight18 kDa
Observed Molecular Weight 21 kDa
GenBank Accession NumberBC000275
Gene Symbol CDKN1A
Gene ID (NCBI) 1026
Conjugate Unconjugated
Form Liquid
Purification MethodAntigen affinity purification
Storage Buffer PBS with 0.02% sodium azide and 50% glycerol pH 7.3.
Storage ConditionsStore at -20°C. Stable for one year after shipment. Aliquoting is unnecessary for -20oC storage. 20ul sizes contain 0.1% BSA.

Background Information

CDKN1A (p21, CIP1, WAF1) is a cyclin-dependent kinase inhibitor. CDKN1A binds to and inhibits the activity of cyclin-CDK2 or -CDK4 complexes, and thus functions as a regulator of cell cycle progression at the G1 phase. The expression of CDKN1A is induced by wild-type but not mutant p53 protein, through which CDKN1A mediates the p53-dependent cell cycle G1 phase arrest in response to a variety of stress stimuli. CDKN1A can interact with proliferating cell nuclear antigen (PCNA), and plays a regulatory role in S phase DNA replication and DNA damage repair. CDKN1A was reported to be specifically cleaved by CASP3-like caspases, which thus leads to a dramatic activation of CDK2, and may be instrumental in the execution of apoptosis following caspase activation. Two alternatively spliced variants, which encode an identical protein, have been reported.


Product Specific Protocols
WB protocol for P21 antibody 10355-1-APDownload protocol
IHC protocol for P21 antibody 10355-1-APDownload protocol
IF protocol for P21 antibody 10355-1-APDownload protocol
IP protocol for P21 antibody 10355-1-APDownload protocol
Standard Protocols
Click here to view our Standard Protocols




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The reviews below have been submitted by verified Proteintech customers who received an incentive forproviding their feedback.


Vikas (Verified Customer) (04-23-2024)

Used p21 antibody at 1:1000 dilution for western blotting worked great. Thank You. Highly recommended.

  • Applications: Western Blot
  • Primary Antibody Dilution: 1:1000
  • Cell Tissue Type: SH-SY5Y cell line

Hadil (Verified Customer) (05-24-2023)

I prepared this antibody in odyssey blocker at 1:1000 and incubated at 4 C overnight and seemed to get a good signal for p21. There were some non-specific bands properly caused by long incubation periods. So, i would recommend using it at this concentration for 1.5-2 hr at RT.

  • Applications: Western Blot
  • Primary Antibody Dilution: 1:1000
  • Cell Tissue Type: Mammalian cell lines

Malak (Verified Customer) (04-22-2021)

The best incubation period for this antibody is 1.5 hr at room temperature, longer incubations (especially overnight at 4°C) may result in aspecific bands.

  • Applications: Western Blot
  • Primary Antibody Dilution: 1/1000
  • Cell Tissue Type: Hepatic cancer cell extract

Susan (Verified Customer) (12-03-2019)

We had been having issues with our old P21 antibody and this one worked great.

  • Applications: Western Blot,
  • Cell Tissue Type: keratinocytes, dog

Béatrice (Verified Customer) (09-04-2019)

This is an excellent and specific antibody, without background.When prepared in 3%BSA, it can be reused several times and kept at-20°C

  • Applications: Western Blot,
  • Primary Antibody Dilution: 1/1000
  • Cell Tissue Type: HCT116
P21 Antibody Western Blot, validation (1/1000 dilution) in HCT116 (Cat no:10355-1-AP)