Scientists figured out how to make the muscle‑repair peptide MGF in baker's yeast. They discovered that a yeast enzyme called proteinase B chews the peptide up, so they deleted the gene for that enzyme. This boosted the amount of usable MGF about five times, up to roughly 50 mg per litre, and the product was shown to make human muscle cells grow in a lab test.

Mechano-growth factor (MGF) is a product of a unique muscle-specific splice variant of the insulin-like growth factor I gene. Potential use of MGF to improve regenerative capability of skeletal muscle as well as to prevent neuronal damage has been widely discussed. Human MGF was expressed in Saccharomyces cerevisiae, but the yield of the recombinant protein was low due to its rapid degradation. The proteinase B was identified as the enzyme responsible for MGF processing. A yeast strain with Deltaprb1 deletion was created resulting in a fivefold increase of MGF yield that reached 50 mg/l. The biological activity of recombinant MGF was verified in a proliferation assay employing human postnatal myoblasts.