PLCγ2 function is required for bt/VWF-induced platelet aggegation, TxA2 production, and ATP secretion; Lyn is required for tyrosine phosphorylation of PLCγ2. (A) PLCγ2^–/– platelets agglutinated, but did not aggregate, (B) produce TxA2, or secrete ATP in response to bt/VWF. (C) Lyn was required for tyrosine phosphorylation of PLCγ2 in response to bt/VWF. The error bars represent standard deviation; n = 3. In some cases, the values of the SD were so small that the bars cannot be seen.