Pharmaceutical inhibition of platelet function is the primary therapy for prevention of arterial thrombosis - the most common cause of death and disability in Australia. However, current therapies have limited efficacy. Defining platelet activation mechanisms in order to rationalise more effective antithrombotic approaches is the major focus of my group. This proposal describes the first studies to examine the importance of a family of intracellular signalling enzymes, the Class II phosphoinositide 3-kinases, in platelet function. These studies will define the contribution of these enzymes to platelet production and function and will establish whether their inhibition is an attractive strategy for the prevention of arterial thrombosis.