P21
Also known as: P021
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).
Who's worth your money for P21
Every current seller, ranked by independent evidence — Merit Score, latest COA purity, and live $/mg (size-normalized). Prices refresh daily. Rankings are never paid.
Top Merit pick
Highest Merit Score (86) of 2 scored sellers
$119 · 10mg · 98.6% purity
Best value
Lowest $/mg among scored sellers
$198 · 10mg
Average price
$15.35/mg
Sellers
10
45-day trend
+9.8%
9 of 10 sellers have a current price· 3 stale hidden· 4 unverified hidden
Top Merit pick
🇺🇸 Verified Peptides86via Disclosed Labs · 23h ago
$11.90/mg -22.5% vs avg$119
10mg
- 🇺🇸 Simple Peptide85
via Disclosed Labs · 23h ago
$19.80/mg +29% vs avg$198
10mg
no purity
Prices observed from public storefronts (last 24h), normalized to $/mg. "Evidence" is Merit's 0–100 Merit Score, derived only from observable verification evidence (methodology on /about); "Purity" is the latest independent COA. Some buy links are affiliate links — Merit may earn a commission at no extra cost to you, and where a vendor offers one, the code shown gets you a discount at their checkout. Affiliate status never affects price data, ranking, or the Merit Score (full policy on /disclosure). Research use only.
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About P21
CAS
1246751-68-7
Molecular formula
C27H42N6O8
Sequence
DGGL
Typical dose range
500–750 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)
COAs for P21
4 third-party tests across 2 vendors. Each card links to the full report.
For
P-21
by Verified Peptides· batch P2106260210B
For
P-21
by Skye Peptides· batch P2125-10-001
Purity not on file
For
P21
by Skye Peptides· batch P2125-10-001
Purity not on file
For
P21
by Skye Peptides· batch P2125-10-001
20 citations indexed for P21
Study · 2026
Single-Cell and Multiomics Characterization of p21 in Cancer Progression and Therapeutic Sensitivity
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.
Study · 2026
Exposure to high doses of tyre antioxidant 6PPD causes senescence to induce unexplained miscarriage by suppressing BAZ1B-mediated ubiquitination degradation of P21
Background Unexplained miscarriage (UM) highly occurs and largely limits human reproduction. Cellular senescence is a ubiquitous process that is associated with many human diseases.
Study · 2026
Genomic Disruption of CAMKMT by t(2;11)(p21;q23) Reveals a Glycolytic Reprogramming Mechanism in Acute Myeloid Leukemia
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.
animal · 2026
CRISPR/Cas9 system-mediated p21 knockout impairs the MITF signaling pathway
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.
Study · 2026
Ubiquitin-dependent degradation of p27Kip1 and p21Waf1/Cip1 by AMBRA1 ensures G1 and S phase progression and limits replication stress
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.
Study · 2026
Transcription-independent induction of rapid-onset senescence is integral to healing
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.