INS, also known as insulin preproprotein, is a biologically inactive precursor to the biologically active endocrine hormone insulin. Insulin is an essential hormone for maintaining metabolic homeostasis in the body. To make fully bioactive insulin, pancreatic beta cells initiate synthesis of INS. It is converted into proinsulin by signal peptidases, which remove its signal peptide from its N-terminus. Finally, proinsulin is converted into the bioactive hormone insulin by removal of the C-peptide. Recombinant protein corresponding to aa25-110 of human INS, fused to His-tag at N-terminus, expressed in E. coli. Accession: NP_000198 Molecular Weight: ~11.8kD (109aa), confirmed by MALDI-TOF Biological Activity: Measured in a cell proliferation assay using MCF7 human breast cancer cell. The ED50 for this effect is 4ug/ml. Amino Acid Sequence: MGSSHHHHHH SSGLVPRGSH MGSFVNQHLC GSHLVEALYL VCGERGFFYT PKTRREAEDL QVGQVELGGG PGAGSLQPLA LEGSLQKRGI VEQCCTSICS LYQLENYCN Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20C. Aliquots are stable for 6 months after receipt at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.