Recent years have seen tremendous advances in our understanding of the molecular mechanism of platelet activation. All aspects of signal transduction in platelets from the identification of surface receptors, G proteins, phospholipases, protein kinases and phosphatases, intracellular receptors for inositol phosphates, the Ca2+ regulatory machinery, cytoskeletal constituents to the control mechanism employing cyclic nucleotides has seen an explosion of information regarding their importance and for each constituent in the family of molecules to which they belong. This information has been of...