FcRγ-chain and LAT are not required for TxA2 production, Akt phosphorylation, or αIIbβ3 activation by washed platelets stimulated with bt/VWF. (A) FcRγ-chain–deficient and LAT-deficient platelets agglutinated, but did not aggregate. Fibrinogen (Fg) restored normal aggregation to both the FcRγ-chain^–/– platelets and the LAT^–/– platelets. (B) FcRγ-chain–deficient platelets produced the agglutination-elicited level of TxA2 and secreted the level of ATP elicited by agglutination. LAT-deficient platelets produced the agglutination-elicited level of TxA2, but did not secrete ATP. Fibrinogen (Fg) enhanced TxB2 production and ATP secretion by both the FcRγ-chain^–/– and the LAT^–/– platelets. (C) FcRγ-chain–deficient and LAT-deficient platelets phosphorylated Akt in response to stimulation by bt/VWF. The numbers over the bars represent the amount of TxA2 production (ng/mL) or ATP secretion (nM). 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.