What is P21 (P021)?
P21, later written P021, is a small synthetic compound built from a four-amino-acid stretch of ciliary neurotrophic factor (CNTF), Asp-Gly-Gly-Leu, with an adamantane unit added at its C-terminal end. It comes from Khalid Iqbal's lab in New York and has been studied only in mice and rats. Despite the name, it has nothing to do with the cell-cycle protein p21.
P021 in one table.
| Core | Ac-Asp-Gly-Gly-Leu, CNTF residues 148 to 151 (UniProt P26441) |
|---|---|
| C-terminal unit | 3-carbamoyl-1-adamantyl amide, as registered by the FDA substance registry |
| Formula | C27H42N6O8 |
| Molecular weight | 578.7 g/mol (monoisotopic 578.3064) |
| CAS number | 1246751-68-7 |
| PubChem CID | 56599151 |
| Other names | P21, P-21 |
| Status | Research compound; no registered human trials |
Formula from the FDA substance registry; masses computed by Helion from it. The 578.3 often quoted in papers is the monoisotopic mass, not the average molecular weight.
From an antibody map of CNTF.
Iqbal's group at the New York State Institute for Basic Research in Developmental Disabilities mapped the parts of CNTF recognized by neutralizing antibodies and found an 11-residue stretch, residues 146 to 156, which they called Peptide 6. Its smallest active piece was the tetrapeptide Ac-DGGL-NH2. Adding an adamantylated glycine to the C-terminal end gave the compound first reported in 2010 as P21 and in later papers as P021.
Rodent models only.
Every published study is in animals: normal mice in 2010, aged rats and the 3xTg mouse model of Alzheimer's disease in 2014, and the Ts65Dn mouse model of Down syndrome in 2017. The papers report changes in neurogenesis, synaptic markers and memory tests in those models. Results in rodents describe those systems only.
One 2011 paper on the related CNTF peptides, with Iqbal as a co-author, was retracted in 2026. It is not a P021 paper, and none of the P021 studies cited here carries a retraction or an expression of concern.
P21 is not p21.
In biology, p21 usually means CDKN1A, a cyclin-dependent kinase inhibitor also called CIP1 or WAF1, with tens of thousands of PubMed records of its own. It is unrelated to this compound. Searching for P021 together with CNTF finds the right literature.
No human trials.
ClinicalTrials.gov lists no trials of P021; the studies that share the code are unrelated. It is not an approved drug, and Helion supplies compounds for laboratory research use only.
Not supplied.
Helion does not supply P021. The research library covers the compounds it does supply, and dihexa is another small compound studied in rodent memory models.
Specs and storage by compound.
Questions (7)
What is P21 peptide?
A synthetic compound built from the CNTF tetrapeptide Asp-Gly-Gly-Leu with an adamantane unit added at the C-terminal end, from Khalid Iqbal's lab, studied in mouse and rat models.
Is P21 the same as P021?
Yes. It was first reported in 2010 as P21 and is written P021 in later papers.
What is P021 made from?
Residues 148 to 151 of ciliary neurotrophic factor, acetylated, with a 3-carbamoyl-1-adamantyl amide at the C-terminus.
What is the molecular weight of P021?
578.7 g/mol (C27H42N6O8). The 578.3 often quoted is the monoisotopic mass.
Is P021 related to the p21 protein?
No. The p21 protein, CDKN1A, is a cell-cycle inhibitor and has nothing to do with this compound.
Has P021 been tested in humans?
No. ClinicalTrials.gov lists no trials of it.
Does Helion sell P21?
No.
Published studies (5)
- Neurotrophic peptides incorporating adamantane improve learning and memory, promote neurogenesis and synaptic plasticity in mice
- Enhancement of dentate gyrus neurogenesis, dendritic and synaptic plasticity and memory by a neurotrophic peptide
- Rescue of cognitive-aging by administration of a neurogenic and/or neurotrophic compound
- Disease modifying effect of chronic oral treatment with a neurotrophic peptidergic compound in a triple transgenic mouse model of Alzheimer's disease
- Early neurotrophic pharmacotherapy rescues developmental delay and Alzheimer's-like memory deficits in the Ts65Dn mouse model of Down syndrome
Citations from PubMed for reference. They describe the compound in the literature, not any Helion lot, and nothing here is guidance on use.