BAK/BAX-deficient platelets exhibit functional defects. (A,B) Agonist-induced platelet activation determined by (A) integrin conformational change (JON/A) or (B) P-selectin positive platelets by flow cytometry. Platelets were washed and counts adjusted before 20 minutes incubation with ADP 12.5 µM (37°C) Convulxin 12.5-50 ng/mL RT and PAR4-AP 0.06-0.25 mM RT. n = 3 biological replicates per genotype. (C) Maximal platelet aggregation in response to PAR4-AP (50 µM). Platelets were washed and counts adjusted. Bak^+/+Bax^+/+ (n = 22), Bak^+/+Bax^fl/fl (n = 6), Bak^−/−Bax^fl/fl (n = 27), Bak^+/+Bax^{Pf4∆/Pf4∆} (n = 11), and Bak^−/−Bax^{Pf4∆/Pf4∆} (n = 15) biological replicates. Representative experiment included. (D) Maximal platelet aggregation in response to ADP (1-10 µM) in PRP. Platelet counts were adjusted to 3.3 × 10⁸ cells/mL. n = 3 to 4 mice per genotype. Data are presented as mean ± standard deviation (SD). One-way ANOVA with Dunnett’s multiple comparison test. *P < .05; **P < .005; ***P < .001; n.s., not significant.