Researchers can't fully explain why IGF LR3 outperforms its natural counterpart in preclinical models. Engineered in the 1990s with an arginine substitution and N terminal extension, this synthetic IGF 1 analog shows reduced IGFBP binding Control of satellite cell function in muscle regeneration and its disruption in ageing Nature Reviews Molecular Cell Biology Peptide Therapy IGF 1 LR3 Revolution Health & Wellness Effect of IGF1 on Myogenic Proliferation and Differentiation of Bovine Skeletal Muscle Satellite Cells Through PI3K AKT Signaling Pathway LONG R IGF I