Our research is aimed at understanding the development and function of blood platelets. These tiny, numerous cells initiate and co-ordinate blood clotting (i.e. hemostasis) at wound sites by adhering, aggregating and secreting a wide assortment of molecules. Platelets are also involved in the formation of arterial plaques and pathological clots such as the thrombi that cause heart attacks and strokes, major causes of mortality in the modern world. Many of our insights into the mechanisms of platelet development and function have come from studies of patients with inherited platelet disorders. Our particular interest is alpha granules, secretory vesicles that platelets use to transport and secrete several hundred different kinds of protein. We have identified several proteins and cellular pathways involved in the development of alpha granules in the cells that produce platelets, the bone marrow megakaryocytes.