Activation of satellite cells. Download Scientific Diagram Effect of IGF1 on Myogenic Proliferation and Differentiation of Bovine Skeletal Muscle Satellite Cells Through PI3K AKT Signaling Pathway Mechanisms of IGF 1 Mediated Regulation of Skeletal Muscle Hypertrophy and Atrophy 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 IGF 1 LR3 Dosage: What to Know About Dosing, Safety, and Clinical Use