Oncostatin M (OSM) is a glycoprotein belonging to the interleukin-6 family of cytokines that has functions mainly in cell growth. Oncostatin M (OSM) is considered as a pleiotropic cytokine that signals through cell surface receptors typeⅠand typeⅡ both of which share the similarity of containing protein gp130 and takes part in many bio metabolism processes including liver development, hematopoiesis, inflammation, bone formation, and destruction and possibly CNS development. Oncostatin M (OSM) was previously identified by its ability to inhibit the growth of cells from melanoma and other solid tumors. It also has been reported that OSM, like LIF, IL-6, and G-CSF, can inhibit the proliferation of murine M1 myeloid leukemic cells and can induce their differentiation into macrophage-like cells. The human form of OSM is insensitive between pH2 and 11 and resistant to heating for one hour at 56 degrees but is not stable at 90 degrees. The human OSM is produced as a precursor containing 252 amino acids, whose first 25 amino acids function as a secretory signal peptide and which on removal yields the soluble 227 amino acid pro-OSM. Removal of the C-terminal most 31 amino acids produces the fully active 196 residue form.

> 95 % as determined by SDS-PAGE