Oncostatin M (OSM) is an approximately 30 KDa secreted cytokine belonging to the Interleukin-6 family. Like other members of the IL-6 family such as IL-11, CNTF, and Cardiotrophin-1, OSM plays crucial roles in inflammation, neuroprotection, hematopoiesis, metabolism and development. To test the effect of OSM on cell proliferation, TF-1 cells were seeded into triplicate wells of 96-well plates at a density of 20,000 cells/well with various concentrations of recombinant human OSM. After incubated for 72 hours, cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8(CCK-8). Briefly, 10 µl of CCK-8 solution was added to each well of the plate, then the absorbance at 450 nm was measured using a microplate reader after incubating the plate for 1-4 hours at 37℃. Proliferation of TF-1 cells after incubation with OSM for 72 hours observed by inverted microscope was shown in Figure 1. Cell viability was assessed by CCK-8 (Cell Counting Kit-8 ) assay after incubation with recombinant human OSM for 72 hours. The result was shown in Figure 2. It was obvious that recombinant human OSM significantly increased cell viability of TF-1 cells, the EC50 was 0.08 ng/ml.