MGF

MGF (Mechano Growth Factor) is the IGF-1Ec splice variant of the insulin-like growth factor 1 (IGF-1) gene — specifically its unique 24-amino-acid C-terminal "E-peptide." Unlike liver-derived systemic IGF-1, MGF is produced locally in mechanically stressed or damaged skeletal muscle (and cardiac muscle and bone), acting as an autocrine/paracrine early-repair signal. It is not approved and is supplied for research use only.

What is MGF and how does it differ from regular IGF-1?

The IGF-1 gene is alternatively spliced into isoforms that share the same mature IGF-1 peptide but carry different C-terminal E-peptide extensions; MGF (IGF-1Ec) is the mechano-responsive variant, expressed in muscle after loading or injury rather than circulating from the liver like IGF-1Ea. Its distinguishing feature is that local expression tied to mechanical stress. Compare the related IGF-1 LR3 and IGF-1 DES profiles.

How does MGF work?

The classic finding (Yang and Goldspink, 2002) is that the MGF E-peptide alone can activate quiescent satellite (muscle stem) cells and promote their proliferation — apparently through a mechanism not blocked by IGF-1-receptor antibodies — while mature IGF-1 drives the later differentiation step; this "two-phase" model puts MGF first in the repair cascade. This satellite-cell-activation effect has not been consistently replicated: a later study reported that the synthetic MGF peptide (the C-terminus of unprocessed IGF-1) had no measurable effect on myoblasts or primary muscle stem cells. Because the unmodified E-peptide degrades within minutes, a PEGylated form (PEG-MGF) was developed for research use.

Sources: Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation, Yang S.Y., Goldspink G., FEBS Lett, 2002; 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, Fornaro M., Hinken A.C., Needle S., et al., Am J Physiol Endocrinol Metab, 2013

What does the research on MGF show?

Evidence is preclinical: MGF activates satellite cells and is rapidly upregulated in damaged muscle and in cardiac tissue after myocardial infarction, with neuroprotective signals in models of cerebral ischemia; aged muscle shows a blunted MGF response. There are no controlled human efficacy trials.

Evidence level: preclinical only

What are the safety concerns and regulatory status?

MGF is not approved for human use and has no established human safety profile. It is prohibited in sport at all times by WADA, whose 2026 Prohibited List names Mechano Growth Factors (MGFs) by name under Section S2.3 (Growth Factors and Growth Factor Modulators). See the legal status guide.

Source: WADA Prohibited List (current year)

Why does vendor verification matter, and how does Peptigrity verify?

""MGF" and "PEG-MGF" are distinct products with very different half-lives, and short peptides are easily mislabeled — HPLC purity and mass-spec identity are the objective checks. Peptigrity collects independent third-party Certificates of Analysis for MGF from shops' official channels and verifies each for authenticity before publishing. Because shops choose which COAs to publish, results reflect the batches shops have made public rather than every production batch — a selection bias we state openly. A community-funded Testing Grant to purchase and test vials anonymously is in development. Tests in the database come from independent labs such as Janoshik Analytical, Freedom Diagnostics, and Chromate; the trust score weights independent lab purity and community reviews equally (50/50). See how to read lab results and what is on file on the independent MGF lab tests page.

Educational information only; not medical advice. MGF is not approved for human use. Consult a qualified healthcare provider. Peptigrity does not sell, endorse, or recommend products or vendors.

Frequently asked questions