






P21
p21 is a key cell-cycle regulatory peptide that lets labs explore cell-cycle arrest, DNA-damage response, and senescence pathways with precision. Each 5 mg vial delivers a ready-to-use peptide that reliably induces p21-mediated checkpoint activation in cell cultures—no extra factors, no guesswork. USA-made, HPLC-verified at ≥ 99% purity, and endotoxin-screened (< 0.1 EU/mg), p21 gives you crisp, reproducible data every time.
⚠️ Important Disclaimer
For Research Use Only. Not for human consumption or therapeutic treatment.
P21
KEY HIGHLIGHTS
Checkpoint Activation
Induces p21-driven G1/S arrest in proliferating cells, making it easy to model cell-cycle checkpoints.
DNA-Damage Response
Amplifies p53–p21 signaling in DNA-damage assays, helping you track repair kinetics.
Senescence Studies
Promotes biomarkers of cellular senescence (SA-β-gal, p16) in fibroblast and epithelial cultures.
Tumor-Biology Models
Supports investigations of tumor-suppressor pathways in cancer-cell lines.
Signal-Pathway Clarity
High specificity for CDK inhibition ensures your results focus on p21’s role, without off-target effects.
Easy Prep & Storage
Lyophilized powder—reconstitute in sterile water, store at 2–8 °C, and use within 7 days for consistent activity.


What Is p21 Peptide?
p21 (also called CIP1/WAF1) is a naturally occurring 21-amino-acid peptide that binds and inhibits cyclin-dependent kinases, enforcing cell-cycle arrest. In research, p21 peptide is used to dissect cell-cycle regulation, DNA-damage checkpoints, and senescence mechanisms under tightly controlled lab conditions.

Why Choose p21?
Choose p21 when you need a straightforward, single-reagent solution for cell-cycle and senescence research. Its reliable induction of G1/S arrest and clear activation of DNA-damage pathways make it ideal for mapping tumor-suppressor functions, screening genotoxic agents, or studying aging at the cellular level. Manufactured under ISO standards and verified to ≥ 99% purity, p21 peptide ensures your experiments run smoothly every time.

What Sets p21 Apart?
Unlike broader cell-cycle inhibitors, p21 peptide offers high target specificity and physiological relevance—mimicking the natural inhibitor that cells use to pause proliferation after stress. Its clean, short-acting profile minimizes off-target kinase effects, giving you precise control over checkpoint activation and senescence modeling.
P21 FAQs
What is p21 peptide used for in research?
To study cell-cycle arrest, DNA-damage response, and senescence in cell and tissue models.
How does p21 induce checkpoint arrest?
By binding CDK2/cyclin E complexes, it halts the G1–S transition and activates DNA-repair pathways.
What concentration is typical in vitro?
Researchers often use 1–10 µM, adjusted per cell type and assay design.
Can p21 promote cellular senescence?
Yes—treated cells show increased SA-β-gal staining and upregulated p16 levels.
Does p21 affect other kinases?
It’s designed for CDK inhibition, with minimal off-target kinase interactions.
How is p21 peptide reconstituted?
Dissolve in Sterile Water for Injection, mix gently, then use immediately or store at 2–8 °C.
What storage conditions are required?
Store powder at –20 °C; use reconstituted solution within 7 days at 2–8 °C.
Can p21 be combined with genotoxic agents?
Yes—it’s often used alongside DNA-damaging compounds to study checkpoint activation.
Is p21 approved for therapeutic use?
No—strictly for research use only, not for clinical or veterinary applications.
Where can I buy p21 peptide?
Real Peptides offers ISO-certified, USA-manufactured p21 peptide (5 mg), ≥ 99% purity, and low endotoxin—available for research use only.