Description: Interleukin-9 rat recombinant produced in E. coli is a single, non-glycosylated polypeptide chain containing 127 amino acids and having a molecular mass of 14.3 kDa. IL9 is a factor that is thought to be a regulator of hematopoiesis. It has been shown to enhance the growth of human mast cells and megakaryoblastic leukemic cells as well as murine helper t-cell clones. IL-9 is a glycoprotein with a molecular weight of 32-39 that is derived from T-cells, and maps to human chromosome 5. The ED50 as determined by a cell proliferation assay using murine TS1 cells is less than 10 ng/ml, corresponding to a specific activity of > 1.0 × 105 IU/mg.