Platelet ERK5 promotes integrin activation, aggregation, and accumulation under shear by oxLDL-CD36 signaling. Washed human platelets (3 × 10⁸/mL) were pretreated with DMSO or BIX 02188 (10 µM) before stimulation with oxLDL (50 µg/mL). Integrin activation was detected with Alexa Fluor 647-labeled fibrinogen (15 µg/mL) (n = 7) (A), and α granule secretion was detected by PE-labeled P-selectin antibody (n = 7) (B) using flow cytometry. (C) Platelet aggregation over time was measured after washed human platelets (3 × 10⁸/mL) were preincubated with DMSO or BIX 02188 (10 µM) before stimulating with oxLDL (50 µg/mL) (n = 3). (D) Platelet aggregation was measured after gel-filtered mouse platelets (3 × 10⁸/mL) were pretreated with oxLDL (50 µg/mL) at room temperature (RT), before stimulating with 0.2 µM ADP (n = 3). (E) Platelet adhesion over time on immobilized collagen was measured after whole blood from WT C57Bl/6 (n = 5), CD36 null (n = 5), ERK5^flox/flox (n = 6), and ERK5^flox/PF4-cre⁺ (n = 6) mice were stimulated with PBS or oxLDL (50 µg/mL). Data represented as mean ± SEM. P value determined by 2-tailed Student t test (C-D) and 1-way ANOVA with Tukey’s post hoc analysis (A-B), between WT and CD36-null (E), and between ERK5^flox/flox and ERK5^flox/PF4-cre⁺ (E).