peptide wiki

P21

aka P021

Nootropic / Cognitive

Mechanism

P21 (also P021) is a small peptidergic compound — the tetrapeptide core Asp-Gly-Gly-Leu with an N-terminal acetyl and a C-terminal adamantylated glycine amide (Ac-DGGL(A)G-NH2) — derived from an active region (residues ~148–151) of human ciliary neurotrophic factor (CNTF). It was designed and characterized in the Khalid Iqbal laboratory at the New York State Institute for Basic Research in Developmental Disabilities (NYS IBR). It is an experimental, preclinical compound — NOT FDA-approved and NOT tested in humans in published trials. Distinct from the cyclin-dependent kinase inhibitor protein p21/CDKN1A/WAF1 (a completely different gene product; the two share only the name).

Identification

CAS number1246751-68-7
Molecular formulaC27H42N6O8
SequenceDGGL
Typical dose500–750 mcg/day intranasal (research use); 250–1000 mcg/day range reported
Half-life>6 hours (rodent; estimated, based on parent Peptide 6 and adamantane-modified stability)

Vendors selling P21

VendorSizePriceListed purityTrust
Skye Peptides 10 mg $79.00 90
Verified Peptides 10 mg $119.00 86
Simple Peptide 10 mg $198.00 85
Peptidegurus 5 mg 84
Core Peptides 5 mg $116.00
Genetic Peptide 5 mg $120.00
Paramount Peptides 10 mg $150.00

Research

Single-Cell and Multiomics Characterization of p21 in Cancer Progression and Therapeutic Sensitivity
Zhang W, Ma Q, Zhao H, Li W, Feng Z, Zhong L, Ren Y, Chang L, Li Y, Shi L. · Human mutation (2026) ·

Introduction CDKN1A (encoding p21) is a canonical regulator of cell cycle arrest and genomic stability. However, its functional spectrum within the tumor microenvironment (TME), especially at single-cell resolution, remains insufficiently defined.

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Exposure to high doses of tyre antioxidant 6PPD causes senescence to induce unexplained miscarriage by suppressing BAZ1B-mediated ubiquitination degradation of P21
Zhang W, Liang Y, Sun Y, Wang J, Huang W, Xing S, Zhang Z, Lin Y, Zeng L, Lei Q, Cheng W, Zhao Z, Zhao D, Guo G, Zhang H. · EBioMedicine (2026) ·

Background Unexplained miscarriage (UM) highly occurs and largely limits human reproduction. Cellular senescence is a ubiquitous process that is associated with many human diseases.

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CRISPR/Cas9 system-mediated p21 knockout impairs the MITF signaling pathway
Kim GH, Kim MM. · Journal of biotechnology (2026) · animal

The CRISPR/Cas9 method facilitates targeted disruption of gene sequences, providing a reliable means to analyze gene-dependent regulatory pathways. This study aims to investigate melanogenesis in p21-knockout B16F1 cells generated by the CRISPR/Cas9 system.

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Ubiquitin-dependent degradation of p27Kip1 and p21Waf1/Cip1 by AMBRA1 ensures G1 and S phase progression and limits replication stress
Milletti G, Cadeddu G, Adelantado-Rubio A, Ferraina C, Keuper K, Munk SHN, De Stefanis C, Quacquarini D, Rossi S, Mastronuzzi A, Locatelli F, Grumati P, Cianfanelli V, Nazio F, Bar, et al. · Nucleic acids research (2026) ·

The cell cycle orchestrates the events that lead to cell replication and division. AMBRA1 interacts with the E3 ubiquitin ligase CRL4DDB1 complex to regulate the stability of D-type cyclins, key regulators of the G1-S phase transition. However, whether AMBRA1 has a role in the S phase remains to be elucidated.

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Transcription-independent induction of rapid-onset senescence is integral to healing
Valdivieso K, Rozmaric T, Victorelli S, Jadhav V, Ring NAR, Machcińska-Zielińska S, Schädl B, Dworak H, Klinaki E, Fischer I, Gadecka A, Moskalevska I, Kostrebic S, Kienberger M, M, et al. · Nature cell biology (2026) ·

Cellular senescence plays key roles in tissue repair, tumour suppression and ageing. Here we identify a rapid, transcription‑independent senescence response in skin following injury. Within minutes to hours after wounding, skin cells at the edge of injury display hallmark features of senescence.

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Dihydroxyacetone nanoparticles ameliorate osteoarthritis via P21-mediated regulation of chondrocyte repair
Fang C, Ji Z, Pan Y, Li Z, Liu C, Feng X. · Journal of nanobiotechnology (2026) · animal

Osteoarthritis (OA) is a disease characterized by progressive cartilage degeneration. P21, as a cell cycle regulator, participates in maintaining cartilage homeostasis.

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Relationship between expression of OGFR, P16, P21 and clinicopathological features of colorectal cancer patients
Wang Z, Zhang B, Li Y, Hao X, Wang Y, Qiao T, Yan J. · Journal, genetic engineering & biotechnology (2026) ·
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Subcellular compartmentalization dependent dichotomy of p21 in cancer
Maheshwari M, Harioudh MK. · Molecular biology reports (2026) · review

p21 (Cip1/Waf1/Sdi1) , a widely studied member of the CKI (CDK inhibitor) family, has been designated a negative regulator of cell cycle progression.

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Zfp36l1 Inhibits DNA Damage by Regulating p21-E2F1-Rad51 Signaling During Myogenic Differentiation
Liu Y, Jiang X, Sun J, Wang L, Li J, Liu H, Jiang A, Wu S, Bao W. · International journal of molecular sciences (2026) · animal

Skeletal muscle differentiation relies on transient DNA strand breaks (DSBs), yet excessive DNA damage remains harmful to myogenic progression.

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Quercetagetin-rich flavonoids from marigold induce apoptosis inhibit metastasis of non-small cell lung cancer via the p53/p21 signaling pathway
Dong Z, Cheng X, Lian Y, Wu D, Liu K, Feng X, Xue Q, Chen Q, Wang L. · Frontiers in oncology (2026) · animal

Non-small cell lung cancer (NSCLC) remains a leading cause of cancer-related mortality worldwide, with limited therapeutic efficacy and severe side effects associated with conventional chemotherapy, creating an urgent need for safe and effective natural anti-tumor agents.

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Coal Dust-Mimetic Carbon Nanoparticles Induce Colonic Epithelial Cell Senescence via p16/p21 Dual Pathways and Promote Colonic Inflammatory Response
Wang Y, Zhang C, Li X, Li S, Jiang W, Duan B, Liu X, Zhou S, Zhang Y. · Journal of gastroenterology and hepatology (2026) · animal

Background and aim The incidence of inflammatory bowel disease among coal miners is globally higher than that in the general population; however, the underlying pathogenic mechanisms remain unclear.

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Ubiquitin-specific protease 11 promotes tubular cell senescence via inhibiting p53 ubiquitin degradation during renal fibrosis
Wang X, Ning M, Wang H, Li J, Xie X, Xie H, Li L, Sun X, Lu L, Zhang Y, Zhou L, Xu C, Shen Q, Lu L, Xu H. · Cellular signalling (2026) · animal

Emerging evidence has established that renal tubular epithelial cell (TEC) senescence is an essential driver of renal fibrosis, while the activation of p53/p21 pathway plays a key role in initiating TEC senescence.

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Study to Assess Safety and PET Imaging Characteristics of a Novel Senescence-specific Radiotracer [18F]FPyGal (2-[Fluorine-18]Fluoro-3-pyridinyl-β-D-galactopyranoside)
· ClinicalTrials.gov (2021) · rct

It is of particular interest to find out whether it is possible to use the novel radiotracer \[18F\]FPyGal to be tested to detect areas after standard tumor therapy that contain resistant (therapy-resistant) tumor cells.

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AI Colorectal Polyp Detection
· ClinicalTrials.gov (2021) · rct

This study is intended to demonstrate the superiority of colorectal polyp detection using computer-assisted colonoscopy compared to conventional colonoscopy.

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Effect of holoBLG on Cat Allergic Patients
· ClinicalTrials.gov (2021) · rct

The aim of the study is to investigate the antigen-unspecific effect of a 3 months supplementation with a food for special medical purposes (FSMP) in form of a lozenge containing beta-lactoglobulin (BLG), iron, retinoic acid, zinc and polyphenols (holo-BLG) in patients with allergic rhinoconjunctivitis caused by cat (h…

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Testing Atorvastatin to Lower Colon Cancer Risk in Longstanding Ulcerative Colitis
· ClinicalTrials.gov (2021) · rct

This phase II trial studies the effect of atorvastatin in treating patients with ulcerative colitis who have a dominant-negative missense P53 mutation and are at risk of developing large intestinal cancer. Patients with ulcerative colitis are known to have an increased risk of developing large intestinal cancer.

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Biological Effect of Vitamin D in Patients With Urothelial Carcinoma
· ClinicalTrials.gov (2020) · rct

The study population will be 50 women or men diagnosed with urothelial cancer candidates to undergo cystectomy as part of their antitumor treatment.

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Neoadjuvant Dabrafenib + Trametinib for AJCC Stage IIIB-C BRAF V600 Mutation Positive Melanoma
· ClinicalTrials.gov (2014) · rct

This is an open label, single centre, phase II study of neoadjuvant drug treatment with dabrafenib + trametinib in patients with resectable American Joint Committee on Cancer (AJCC) Stage IIIB-C BRAF V600 mutation positive melanoma.

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Pioglitazone to Treat Adults Undergoing Surgery for Non-small Cell Lung Cancer
· ClinicalTrials.gov (2008) · rct

Background: * Pioglitazone is a drug that belongs to the class of antidiabetic agents called thiazolidinediones. It is approved for treatment of type 2 diabetes mellitus. * Research suggests that the thiazolidinediones may have anticancer activity that can reduce cancer risk or cause tumors to shrink.

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Rosiglitazone Maleate in Treating Patients With Oral Leukoplakia
· ClinicalTrials.gov (2006) · rct

This phase II trial is studying how well rosiglitazone works in preventing oral cancer in patients with oral leukoplakia. Chemoprevention is the use of certain drugs to keep cancer from forming, growing, or coming back. The use of rosiglitazone may keep cancer from forming in patients with oral leukoplakia

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