Animal-free Recombinant Human IL-9 is expressed from human 293 cells as a glycoprotein monomer with apparent molecular mass of 38 to 48 kDa. IL-9 is produced in a human cell expression system with serum-free, chemically defined media. It stimulates cell proliferation and also prevents apoptosis. IL-9 acts as a regulator for a variety of hematopoietic cells. It enhances the expansion and recruitment of mast cells and eosinophils. This cytokine is greater than 95% pure.