IGF 1 LR3 does not promote growth in late gestation growth restricted fetal sheep American Journal of Physiology Endocrinology and Metabolism American Physiological Society HGH IGF Penis Growth Retrovirus Therapy: What the Evidence Really Shows IGF 1 LR3 EQUINE MEDCARE RUO Recombinant Human IGF 1 LR3 Protein What is IGF 1 LR3? Insulin Like Growth Factor 1 Long R3 (IGF 1 LR3) is a modified version of IGF 1 with a longer half life, making it significantly more potent and effective for muscle growth, Increased testicular insulin like growth factor 1 is associated with gonadal activation by recombinant growth hormone in immature rats Reproductive Biology and Endocrinology Springer Nature Link