Oncostatin-M, also known as OSM, is a growth regulator belonging to the interleukin-6 group of cytokines. It is expressed mainly by monocytes, activated T cells and Kaposi’s sarcoma cells. OSM signals through two types of receptors; one is composed of gp130 and LIFR, and the other is composed of gp130 and OSMR. OSM regulates IL-6, G-CSF and GM-CSF production, and thus is involved in hematopoiesis, neurogenesis and osteogenesis. OSM displays both stimulatory and inhibitory effects, so its categorization as pro-inflammatory or anti-inflammatory cytokine is still controversial.