Oncostatin M (OSM) is a glycoprotein belonging to the interleukin-6 family of cytokines that includes leukemia-inhibitory factor, granulocyte colony-stimulating factor, and interleukin 6. OSM encodes a growth regulator, which Inhibits the proliferation of a number of tumor cell lines. It stimulates proliferation of AIDS-KS cells. OSM regulates cytokine production, including IL-6, G-CSF and GM-CSF from endothelial cells. OSM is considered as a pleiotropic cytokine that initiates its biological activities through specific cell surface receptors. The low affinity LIF receptor that shares the similarity of containing protein gp130 has now been identified to be a component of a high- affinity OSM receptor that will transduce OSM signals. OSM has also been shown to play a role in both pro and anti-inflammatory actions. OSM may also be involved in many biometabolism processes including liver development, haematopoeisis, inflammation, bone formation and destruction and possibly CNS development.