Impaired thrombus formation in mice with mutations in SLP76 tyrosines. (A) Schematic of SLP76 KI mice. (B) Thrombus formation in Y112/128F (n = 12), Y145F (n = 13), WT littermate control (n = 16), or C57BL/6 (n = 8) mice after FeCl₃-induced injury of the carotid artery. Representative flow traces for each genotype are shown, and arrows indicate when 10% FeCl₃ was applied. The time to vessel occlusion in individual mice for each group is shown in the scattergram. Symbols above the 30-min threshold represent mice that had not occluded when the experiment was terminated. Horizontal bars show the mean occlusion time for WT animals. Unstable mice (U) formed a transient occlusion that resolved. Ratios of the number of animals that did not form occlusion to the number of animals that did were compared between WT and SLP76 KI mice using Fisher's exact test. (C) Platelets in whole blood were perfused over collagen-coated slides at variable shear rates for 4 min (n = 3). Representative phase-contrast images after perfusion are shown (top, shear rate = 400 s⁻¹; bottom, shear rate = 1,300 s⁻¹). Bar, 10 μm. (D and E) Thrombus volume (D) and thrombi surface area (E) were measured at a shear rate of 1,300 s⁻¹ at five surface locations (mean ± SEM). Statistical analysis was performed using the Student's t test. *, P < 0.05; and **, P < 0.01 for differences between mutant and WT platelets.