OSM（ONCOSTATIN M）is a member of a cytokine family that includes leukemia-inhibitory factor, granulocyte colony-stimulating factor, and interleukin 6. This gene encodes a growth regulator which inhibits the proliferation of a number of tumor cell lines. It regulates cytokine production, including IL-6, G-CSF and GM-CSF from endothelial cells.OSM is mapped on 22q12.2. OSM has the ability to inhibit the growth of human A375 melanoma cells but not normal human fibroblasts. Treatment with recombinant OSM leads to the inhibition of proliferation and changes in cellular morphology of a number of tumor cell lines derived from a wide variety of tissue types. OSM also has the ability to inhibit the proliferation of murine M1 myeloid leukemic cells and can induce their differentiation into macrophage-like cells, a function shared by LIF, CSF3, and IL6. The direction of gene transcription was telomeric to centromeric, with the OSM gene located upstream of the LIF gene.