Erbstatin blocks platelet activating factor-induced protein-tyrosine phosphorylation, polyphosphoinositide hydrolysis, protein kinase C activation, serotonin secretion and aggregation of rabbit platelets.

The role of protein-tyrosine phosphorylation in the signal transduction of platelet activating factor (PAF) was investigated in rabbit platelets with a range of synthetic compounds that inhibit protein-tyrosine kinases. In particular, erbstatin (IC50 approximately 20 micrograms/ml) abrogated a wide range of platelet responses to PAF, including tyrosine phosphorylation of cellular proteins, polyphosphoinositide turnover, activation of membranous protein kinase C, platelet aggregation, and serotonin secretion. With about a third of the potency of erbstatin, compound RG50864 also inhibited many of these responses, whereas at 100 micrograms/ml, genistein, 670C88 and ST271 were without effect. Finally, the ability of thrombin to cause platelet aggregation and serotonin secretion was also compromised by erbstatin.