CD41, also known as integrin α2b and GPIIb, is a transmembrane glycoprotein that is expressed by platelets and megakaryocytes. It was reported that CD41 is also expressed on hematopoietic progenitors. CD41 associates with CD61 (integrin β3) to form complexes that interact with fibrinogen, fibronectin, von Willebrand factor, and thrombin. CD41 is required for platelet adhesion and aggregation. Defect of CD41 leads to disorders of coagulation.