Thrombopoietin （TPO） is a glycoprotein hormone that plays a crucial role in the regulation of platelet production and megakaryocyte differentiation. The human TPO protein consisting of 174 amino acids is primarily produced in the liver and kidneys. TPO acts by binding to its receptor, the c-Mpl receptor, which is expressed on the surface of hematopoietic stem cells and megakaryocytic progenitor cells. Upon binding, TPO activates signaling pathways that promote the proliferation and differentiation of megakaryocytes, leading to increased platelet production. TPO is essential for maintaining normal platelet levels in the blood and is a key regulator of thrombopoiesis.