Purity ≥ 90% as determined by SDS-PAGE and HPLC. Human Cell Expression Cytokines: Expression of proteins in our Human 293-cell expression system is a cost-effective and scalable production method for high-authenticity, recombinant human proteins. Functional activities of human proteins depend on proper folding, phosphorylation, disulfide bridge formation, and proteolytic processing or appropriate glycosylation. Ideally, recombinant human proteins are produced in human cells that are more authentic in terms of both physical properties and biochemical functions. However, the current process of human cell expression requires a large quantity of DNA and medium supplemented with bovine serum. Hence, it is often a daunting task to produce sufficient amount of high quality proteins for drug discovery or diagnostic development (1-100mg) at acceptable cost. United States Biological is now supplying a high yield, cost-effective and versatile system to produce active recombinant human proteins in