IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is an 83-amino acid recombinant analog of human IGF-1 in which the glutamic acid at position 3 is replaced with arginine and a 13-amino acid N-terminal extension peptide is added. These modifications significantly reduce binding affinity for IGF-binding proteins (IGFBPs), resulting in enhanced bioavailability and prolonged activity compared to native IGF-1. In research contexts, IGF-1 LR3 is used to study IGF-1 receptor (IGF-1R) signaling, PI3K/Akt and MAPK/ERK pathway activation, cell proliferation, differentiation, and anti-apoptotic mechanisms. It is widely used in cell culture systems as a serum-free media supplement and in pharmacological studies of growth factor biology. Sold for qualified laboratory and research purposes only. Not for human or animal consumption.