Thrombopoietin is a glycoprotein hormone produced mainly by the liver and the kidney that regulates the production of platelets by the bone marrow. It stimulates the production and differentiation of megakaryocytes, the bone marrow cells that fragment into large numbers of platelets Synonyms: Megakaryocyte colony-stimulating factor, Myeloproliferative leukemia virus oncogene ligand, C-mpl ligand, ML, Megakaryocyte growth and development factor, MGDF, TPO, MKCSF, MPLLG, MGC163194, THPO