A thrombopoietin receptor agonist; induces proliferation of Ba/F3 cells expressing human MPL (EC50 = 84 nM) but not of those expressing mouse Mpl; increases the number of circulating platelets in a transgenic mouse model expressing human MPL at 0.3-10 mg/kg per day and increases the number of megakaryocytes in the bone marrow at 10 mg/kg per day