Mutations of the 3 C-terminal tyrosines or tyrosine 136 of LAT inhibit platelet aggregation and secretion in response to Cvx. (A,B) Platelets from the different mouse strains were stimulated with increasing concentrations of Cvx, and aggregation was assessed using a Chrono-log (Payton Associates) dual channel aggregometer under stirring at 900 rev/minute. The profiles shown are representative of 4 independent experiments. (C,D) To measure dense granule secretion, 5-hydroxy[¹⁴C]tryptamine[e]labeled platelets were stimulated by different concentration of Cvx. Results are expressed as a percentage of 5-hydroxy[¹⁴C]tryptamine (serotonine) secretion and are means (± SEM) of 5 independent determinations.