Summary
MGF refers to a peptide from the unique tail of IGF-1Ec, a form of IGF-1 produced by muscle after mechanical stress. Early cell studies suggested it expanded muscle stem cells, but a later independent study found no effect of the synthetic peptide on myoblasts or muscle stem cells.
Structure
A synthetic peptide matching the unique C-terminal E domain of the IGF-1Ec splice variant. PEG-MGF has polyethylene glycol attached to extend its half-life.
How it works
The hypothesis is that the E-domain peptide acts independently of the IGF-1 receptor to activate satellite cells. The receptor and mechanism, if any, remain unidentified.
Research use cases
Areas where MGF and PEG-MGF has been studied. Inclusion here does not mean it works for that purpose.
- Muscle satellite cell research
- Cardiac and neuroprotection models
What the research found
Original hypothesis
Yang and Goldspink reported that the MGF E peptide increased myoblast proliferation while delaying differentiation, unlike mature IGF-1.1
Failure to replicate
A 2014 study testing synthetic MGF peptide on mouse and human myoblasts and primary muscle stem cells found no effect on proliferation or differentiation.2
Safety and open questions
No human data.
Regulatory status
Not approved. PEG-MGF remains in FDA compounding Category 2.
Status was accurate when this page was last reviewed on October 26, 2026. Regulations change; check with the relevant authority before relying on it.
MGF and PEG-MGF: common questions
Does MGF work?
The evidence is contested. The original positive findings have not held up in at least one careful independent replication, so its effect remains unproven even in cells.
Is MGF and PEG-MGF approved for human use?
Not approved. PEG-MGF remains in FDA compounding Category 2.
References
- Yang SY, Goldspink G. (2002). Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation. FEBS Letters.
- Fornaro M, Hinken AC, Needle S, et al. (2014). Mechano-growth factor peptide, the COOH terminus of unprocessed insulin-like growth factor 1, has no apparent effect on myoblasts or primary muscle stem cells. American Journal of Physiology. Endocrinology and Metabolism.
Links open a PubMed search for the exact title, or the original source where one is given.