<prompt> Thromboxane A, is produced mainly byVascular endotheliumPlateletsLiverDamaged tissue  <response>: Platelet Activating FactorPAF secreted by platelets act G protein-coupled receptor to produce arachidonic acid derivative like Thromboxane A2 Ref: Ganongs Review of Medical Physiology Twenty-Third Edition pg no:75 Thromboxane A2 is produced by activated platelets during hemostasis and has prothrombotic activity. It activates new platelets and increase platelet aggregation. 