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
Alpha Omega 10 mg $198.00
Core Peptides 5 mg $116.00
Genetic Peptide 5 mg $120.00
Paramount Peptides 10 mg $127.50
realpeptides.co $100.00

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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Genomic Disruption of CAMKMT by t(2;11)(p21;q23) Reveals a Glycolytic Reprogramming Mechanism in Acute Myeloid Leukemia
Li S, Yang X, Fang P, Li D, Lang X, Chen H, Xiao S, Chen Y. · Current medicinal chemistry (2026) ·

Introduction The t(2;11)(p21;q23) translocation without KMT2A rearrangement has been reported in ~16 hematologic neoplasms, but its molecular target(s) remain unknown. We aimed to identify the genes disrupted by this translocation and to clarify its contribution to Acute Myeloid Leukemia (AML) pathogenesis.

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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) ·

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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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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Use of ACU-D1 in HPV Associated Vulvar and Perianal Lesions in People With HIV
· ClinicalTrials.gov (2026) · rct

The goal of this study is to test the maximum tolerated dose of ACU-D1 in HIV-positive people with HPV-associated vulvar and perianal lesions.

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Green Propolis Extract and Royal Jelly in Hypertensive Patients and/or With Chronic Kidney Disease
· ClinicalTrials.gov (2024) · rct

This work aims to evaluate the effects of the association of green propolis extract with royal jelly on inflammation and oxidative stress in participants with chronic kidney diseases (CKD) and Systemic arterial hypertension (SAH), in a longitudinal, randomized, double-blind, placebo-controlled clinical trial that will…

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Assessment of Vivity With French Clinical Data Related to the Toric Model Study
· ClinicalTrials.gov (2022) · cohort

Presbyopia-correcting implant (PC-IOL): AcrySof IQ Vivity (Alcon) has been evaluated in 2 large pivotal trials (US and OUS trials). These tests showed that this PC-IOL restored intermediate visual acuity (IVA) and near visual acuity (NV A) superior to that of the reference monofocal AcrySof implant.

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Senescence and the Early Ageing Phenotype After Chemotherapy for Testicular Cancer: the SEA-CAT Study
· ClinicalTrials.gov (2019) · rct

Cisplatin-combination chemotherapy causes inevitably DNA damage by platinum-DNA adduct formation of both tumor cells but also healthy cells.

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Rosuvastatin in the Treatment of Rectal Cancer
· ClinicalTrials.gov (2015) · rct

This study will evaluate whether the addition of Rosuvastatin to standard chemoradiation therapy for the treatment of locally advanced rectal cancer may improve the pathological response rate and survival compared to standard chemoradiation therapy alone.

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Inferior Vena Cava (IVC) Size in Acute Renal Failure
· ClinicalTrials.gov (2014) · cohort

Bedside ultrasonographic assessment of IVC size and IVC collapsibility index can be used to guide the management of patients with acute kidney injury with and without volume overload in the intensive care unit

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Muscle Force Assessment in the Intensive Care Unit and in Primary Myopathies
· ClinicalTrials.gov (2006) · cohort

The primary aim of the project is to apply the non-invasive stimulated muscle force assessment system to i) intensive care unit patients and ii) patients with primary myopathy or subclinic myopathy (e.g., Duchenne muscular dystrophy, Myotonia, MH).

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Phase I Trial of Docetaxel and Low-Dose Fractionated Radiation in the Treatment of Metastatic or Recurrent NSCLC
· ClinicalTrials.gov (2004) · rct

The purpose of this study is to assess the maximum tolerated dose of low-dose radiation in combination with Docetaxel in recurrent or metastatic non-small cell lung cancer for second-line therapy.

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