He joined the faculty at University of Memphis in 1976. Signal transduction is studied using platelets from knockout mice and human platelets. A scanning electron micrograph of a resting platelet Approximately 2 m in diameter in the resting state, platelets do not exhibit homeotypic cell-cell aggregation or adhesion to the vessel wall. A platelet is an anucleate cytoplasmic fragment of a bone marrow megakaryocyte, specialized to play a crucial role in hemostasis. Platelets are rich in myosin and actin cytoskeletal elements which facilitate a dramatic shape change phenomenon upon activation.
Shape change occurs as a result of agonist stimulation.
Contact with collagen fibers causes platelet activation. Platelets are then able to secrete storage granule contents which recruit and activate more platelets at the wound site. When the process runs amok, a platelet aggregate becomes a thrombus which may occlude the vessel at the wound site or detach and as an embolus, and block the vasculature downstream, leading to a stroke or heart attack. For this reason, platelet interaction with soluble Fg, which plays a central role in platelet aggregation, interests us.