All tags p21 p21 and DNA binding proteins

p21 and DNA binding proteins

p21 regulates transcription, replication and repair. Find products to investigate p21 interacting proteins PCNA, E2F1, STAT3, c-Myc.

​​p21 influences replication, transcription and repair following interaction with DNA binding/interacting elements. p21 binds to proliferating cell nuclear antigen (PCNA) thereby affecting DNA synthesis and replication1. p21 also directly binds to E2F1, STAT3 and Myc and inhibits transactivation of their respective promoters. 


PCNA is a cofactor of DNA polymerase δ and ε1. In addition to inhibiting PCNA-regulated replication, studies have shown p21 to be a negative regulator of PCNA’s accidental involvement in repair of undamaged DNA2.

TypeReagent nameDescriptionAbID
AntibodyAnti-PCNA antibodyType: Mouse monoclonal antibody
Reactivity: Hu, Mo, Rt, others
Applications: WB, ICC/IF, others
KitPCNA SimpleStep ELISA® kitQuantitatively measure PCNA levels in various sample types.

Reactivity: Hu
Range: 50 ng/ml - 0.78 ng/ml
Method: Colorimetric
ProteinRecombinant Human PCNAHuman PCNA protein for use in WB and as control3.ab172197
Small molecule compoundT2AA
(PCNA inhibitor)
Inhibits the interaction pf PCNA/PIP-box peptide (IC50 = 1 μM) and that of PCNA and p21, abolishing PCNA DNA pol. δ interaction4.ab146970


E2F is a tumor suppressor and functions as a negative regulator of cell cycle progression5. Binding of p21 to E2F1 can result in inhibition of apoptosis and the implication of p21 in oncogenesis6.

TypeReagent nameDescriptionAbID
AntibodyAnti-E2F1 antibodyType: Rabbit monoclonal antibody
Reactivity: Hu, Mo, Rt, others
Applications: WB, ICC/IF, IP, others
ProteinRecombinant Human E2F1Human E2F1 protein for use in WB and as control.ab152349


STAT3 is involved in inhibition of apoptosis in cancer cells with its phosphorylated form appearing in a a number of tumor types7,8. p21 is implicated as an inhibitor of STAT3 signaling providing new insights into the role of p21 in cancer regulation9.

TypeReagent nameDescriptionAbID
AntibodyAnti-STAT3 antibodyType: Rabbit monoclonal antibody
Reactivity: Hu, Mo, Rt
Applications: Flow Cyt, ICC/IF, IHC-P, WB
Anti-STAT3 (phospho Y705) antibodyType: Rabbit monoclonal antibody
Reactivity: Hu, Mo, Rt
Applications: ICC/IF, IHC-P, IP, WB
KitSTAT3 (pY705) + total STAT3 ELISA KitMeasure STAT3 levels in various sample types.
Reactivity: Hu, Mo, Rt
Small molecule compoundStattic
(STAT3 inhibitor)
Selective STAT3 inhibitor that induces apoptosis in vitro and in vivo.ab120952
Tubstat3 Cpd21
(STAT3 inhibitor)
Inhibits tubulin polymerization and phosphorylation of STAT3 inhibition with an IC50 value of 0.2 μM10.ab146906


p21 is inhibited by c-Myc to promote cell proliferation11. p21 in turn represses c-Myc by binding to the N-terminal region and preventing c-Myc-MAX dimerization6. An unexplored relationship between c-Myc and p21 might exist causing cellular oncogenicity and proliferation.

TypeReagent nameDescriptionAbID
AntibodyAnti-c-Myc antibodyType: Rabbit monoclonal antibody
Reactivity: Hu, Mo, Rt
Applications: WB, ICC/IF, Flow Cyt, IHC-P, IP
Kitc-Myc Transcription Factor Assay KitQuantify c-Myc activation in nuclear extracts in a sensitive, colorimetric high-throughput format.ab207200
Small molecule compound10058-F4
(c-Myc inhibitor)
Cell-permeable c-Myc-Max dimerization inhibitorab145065


  1. Cayrol, C., Knibiehler, M. & Ducommun, B. p21 binding to PCNA causes G1 and G2 cell cycle arrest in p53-deficient cells. Oncogene 16, 311–320 (1998). Read more
  2. Prives, C. & Gottifredi, V. The p21 and PCNA partnership: A new twist for an old plot. Cell Cycle 7, 3840–3846 (2008). Read more
  3. Tsurimoto, T., Shinozaki, A., Yano, M., Seki, M. & Enomoto, T. Human Werner helicase interacting protein 1 (WRNIP1) functions as a novel modulator for DNA polymerase δ. Genes to Cells 10, 13–22 (2004). Read more
  4. Punchihewa, C. et al. Identification of small molecule proliferating cell nuclear antigen (PCNA) inhibitor that disrupts interactions with PIP-box proteins and inhibits DNA replication. J. Biol. Chem. 287, 14289–14300 (2012). Read more
  5. Yamasaki, L. et al. Tumor induction and tissue atrophy in mice lacking E2F-1. Cell 85, 537–48 (1996). Read more
  6. Abbas, T. & Dutta, A. p21 in cancer: intricate networks and multiple activities. Nat. Rev. Cancer 9, 400–414 (2009). Read more
  7. Xin–hua, B. & Rui–yu, L. Progress in research on correlation among STAT3, CyclinD1, P21 genes and tumors. J. Otol. 7, 19–24 (2012). Read more
  8. Johnston, P. A. & Grandis, J. R. STAT3 signaling: anticancer strategies and challenges. Mol. Interv. 11, 18–26 (2011). Read more
  9. Coqueret, O. & Gascan, H. Functional interaction of STAT3 transcription factor with the cell cycle inhibitor p21WAF1/CIP1/SDI1. J. Biol. Chem. 275, 18794–800 (2000). Read more
  10. Lai, M.-J. et al. N -Sulfonyl-aminobiaryls as Antitubulin Agents and Inhibitors of Signal Transducers and Activators of Transcription 3 (STAT3) Signaling. J. Med. Chem. 3, 150813150116006 (2015). Read more
  11. Gartel, A. L. et al. Myc represses the p21(WAF1/CIP1) promoter and interacts with Sp1/Sp3. Proc. Natl. Acad. Sci. U. S. A. 98, 4510-5 (2001). Read more

Sign up