Platelet adhesion, aggregation, and clot retraction are impaired at low kindlin-3 levels. (A) Washed platelets were stimulated with 0.01 U/mL thrombin and allowed to adhere to coated fibrinogen for 10 minutes in the presence or absence of 3 mM Mn²⁺. (B) Washed platelets were either left untreated or were plated on fibrinogen in the presence of 1 mM Mn²⁺ and 0.01 U/mL thrombin. FAK Y397 phosphorylation was densitometrically quantified from at least 3 different Western blots and normalized for GAPDH levels. Values are shown as mean ± SD. Data were statistically analyzed by Student t test. (C) Aggregates of K3+/+, K3+/n, K3n/n, and K3n/− platelets in response to 0.1 U/mL thrombin. (D) Platelet aggregation assays with K3+/+, K3+/n, K3n/n, K3n/−, and K3−/− platelets in response to 0.1 U/mL thrombin. (E) Clot retraction of platelets from K3+/+, K3+/n, K3n/n, K3n/−, and K3−/− mice. *P < .05; **P < .01; ***P < .001. n.s., not significant.