Defective functional responses in EXOC3 KO platelets after GPVI stimulation and whole blood thrombus formation over collagen. (A-B) Washed platelets (2 × 10⁸/mL) from WT and EXOC3 KO platelets were assessed for CRP-induced platelet aggregation and dense granule secretion responses by lumi-aggregometry. Representative aggregation (Ai-iii) and secretion (Aiv-vi) traces in response to increasing concentrations of CRP are shown. Quantified area under the curve (AUC) (Bi) and peak ATP (Bii) values were calculated to determine changes in aggregation and secretion, respectively. (C) Washed platelets (2 × 10⁷/mL) from WT and EXOC3 KO mice were treated with indicated concentrations of CRP (0.1-30 µg/mL) for 10 minutes, fixed, and analyzed for integrin α_IIbβ₃ activation (i) and α-granule secretion of P-selectin (CD62P) (ii) by flow cytometry using a JON/A and P-selectin antibody, respectively. (D) Anticoagulated whole blood from WT and EXOC3^−/− mice was loaded with 2 µM DiOC6 for 10 minutes and subsequently perfused over a collagen-coated surface (50 µg/mL) at 1000 s⁻¹ for 3 minutes. Representative images of thrombus accumulation (i) and quantification of change in percent surface coverage over time (ii) and end point at 3 minutes (iii) are provided (scale bar, 200 µm). Data are presented as the mean ± standard error of the mean. n = 5-7 (A-B); n = 7 (C); n = 5 (D). *P < .05, **P < .01, ***P < .001, ****P < .0001 vs indicated sample.