IGF1-LR3 (Insulin-like Growth Factor 1 Long Arg3) is a synthetic, modified form of IGF-1 consisting of 83 amino acids. The Arg3 substitution at position 3 and a 13-amino-acid N-terminal extension significantly reduce binding to IGF-binding proteins, resulting in enhanced bioavailability and a longer half-life compared to native IGF-1. Widely used in cell culture and in vivo research models studying proliferation, differentiation, and metabolic signaling. Provided as a high-purity lyophilized research compound.