FOXO4-DRI FAQ: Your Questions Answered
The questions below are the ones that come up specifically about FOXO4-DRI, rather than general peptide questions that apply to everything.
Overview
Common questions: whether FOX04-DRI and Proxofim are the same (yes), what DRI means, how it differs from small-molecule senolytics, and why the chain ends in so many arginines.
What FOXO4-DRI actually is
FOXO4-DRI is a lab-made peptide that blocks two proteins, FOXO4 and p53, from holding onto each other inside worn-out "senescent" cells. In the 2017 study that introduced it, breaking that grip caused senescent cells in the dish to self-destruct while healthy cells were left alone. It is studied in cell and animal research on how senescent cells build up with age and damage. You will also see it spelled FOX04-DRI (with a zero) or sold as Proxofim — same molecule.
Supplied for laboratory research use only — not for human or animal use.
Third-party tested by HPLC and LC-MS, ≥99% purity, with a Certificate of Analysis on every order. Ships across Canada.
Technical detail below
FOXO4-DRI — common questions
Are FOXO4-DRI, FOX04-DRI and Proxofim the same thing?
Yes. FOXO4 is the protein name (with the letter O); FOX04 with a zero is a common misspelling on labels and certificates, and Proxofim is a trade-style name used by some suppliers. All refer to the same D-retro-inverso peptide.
What does DRI stand for?
D-Retro-Inverso. The peptide is built from D-amino acids assembled in reverse order. The side chains end up in roughly the same spatial positions as the natural FOXO4 fragment, but the backbone is resistant to proteases.
How is it different from small-molecule senolytics?
Small-molecule senolytics studied in the literature, such as navitoclax or dasatinib with quercetin, act on anti-apoptotic or kinase pathways. FOXO4-DRI instead targets a protein–protein interaction, FOXO4 binding to p53, that senescent cells depend on.
Why does the sequence end in so many arginines?
The arginine-rich stretch comes from the HIV-TAT cell-penetrating peptide. It helps the molecule cross cell membranes, and it is also why the peptide is strongly positively charged and clings to glass.
Why can the measured content exceed 10 mg?
Fill weights carry a tolerance, and content assays measure the peptide actually present. Our batch FOX4-401-002 measured 12.37 mg in a 10 mg vial at 99.724% purity (Janoshik #93523).
What FOXO4-DRI is studied for
The founding study showed that senescent cells rely on FOXO4 holding p53 in the nucleus. Interfering with that interaction caused p53 nuclear exclusion and intrinsic apoptosis selectively in senescent cells in culture (Baar et al., Cell 2017).
The same study examined doxorubicin-induced senescence, fast-ageing XpdTTD/TTD mice and naturally aged mice, reporting changes in fur density, fitness and renal markers.
Studied in hydrogen-peroxide-induced senescent TM3 Leydig cells and aged mice for effects on the testicular microenvironment (Zhang et al., Aging 2020).
At 25 µM in vitro it removed a large share of late-passage (senescent-enriched) human chondrocytes while sparing early-passage cells, without improving cartilage-forming capacity (Huang et al., Front Bioeng Biotechnol 2021).
Summarizes published preclinical literature — see the selected references below. Provided for research reference only; not a claim of efficacy or a description of human use.
- Baar MP, Brandt RMC, Putavet DA, et al. Targeted Apoptosis of Senescent Cells Restores Tissue Homeostasis in Response to Chemotoxicity and Aging. Cell. 2017.
- Zhang C, Xie Y, Chen H, et al. FOXO4-DRI alleviates age-related testosterone secretion insufficiency by targeting senescent Leydig cells in aged mice. Aging (Albany NY). 2020.
- Huang Y, He Y, Makarcyzk MJ, Lin H Senolytic Peptide FOXO4-DRI Selectively Removes Senescent Cells From in vitro Expanded Human Chondrocytes. Frontiers in Bioengineering and Biotechnology. 2021.
- Browse current FOXO4-DRI literature on PubMed
References describe in-vitro and preclinical research and are listed for reference only — not evidence of efficacy and not a description of human use.
More FOXO4-DRI reference
Lyophilized and reconstituted storage conditions, plus the practical working window.
Diluent selection, dissolution behaviour, and the calculator preset for this compound.
Which solvents work, why, and what abnormal dissolution behaviour indicates.
The specific chemical routes by which this molecule breaks down, and how to limit each.
Which assays are informative for this molecule, and what to actually check on its COA.
Compound-specific bench practices, and the errors most often made with this molecule.
What to inspect on arrival, and which conditions actually warrant rejecting a vial.
FAQ reference for other compounds
Reviewed for research-use compliance by Kobi Williams, Founder — Popular Peptides Canada. Last reviewed 22 July 2026.
FOXO4-DRI is supplied strictly as a research chemical for in-vitro laboratory and research use only. It is not intended for human or animal consumption, diagnostic, or therapeutic use. This page is educational laboratory-handling reference information — not medical advice, not usage guidance, and not a protocol.