Recombinant human long chain insulin-like growth factor 1 (LR3-IGF1) is an analogue of insulin-like growth factor 1. (LR3-IGF1 has 13 more amino acid chains at the N-terminal end (L) compared to IGF-1 and the glutamic acid at the third position of IGF-1 is replaced by arginine (R3). Natural IGF-1 contains 70 amino acids (7.4 KDa) and LR3-IGF1 contains 83 amino acids (9.11 KDa). Both contain 6 cysteines and a tertiary structure of 3 pairs of disulfide bonds. The biological activity capacity of LR3-IGF1 is 10 times higher than that of IGF-1; 200-1000 times higher than that of insulin. Application areas : cytokines necessary for serum-free cell culture and cytokines for scientific research.