Intracellular CyPA regulates Ca²⁺ mobilization in platelets. (A-B) Defective agonist-induced Ca²⁺ mobilization and impaired SOCE in Cypa^+/+ and Cypa^−/− platelets. Fura-2–loaded Cypa^+/+ (black line) and Cypa^−/− (gray line) platelets before and after stimulation with thrombin (0.02 U/mL) or CRP (10 μg/mL) in the absence (0.5mM EGTA, right) or presence (1mM Ca²⁺, left) of extracellular Ca²⁺. (A) Representative tracings reflecting cytosolic Ca²⁺ concentration ([Ca²⁺]_i). (B) Arithmetic mean of maximal increase in intracellular Ca²⁺ concentrations compared with baseline levels before stimulus (Δ [Ca²⁺]_i ± SD, n ≥ 6 per group). *P < .05; **P < .01; ***P < .001. (C) Fura-2 fluorescence reflecting cytosolic Ca²⁺ concentration ([Ca²⁺]_i) of Cypa^+/+ (black line) and Cypa^−/− platelets (gray line) after stimulation with 5μM thapsigargin for 10 minutes, followed by the addition of 1mM extracellular Ca²⁺. Representative measurements (top panel) and Δ [Ca²⁺]_i ± SD (n ≥ 6 per group) before and after the addition of 1mM Ca²⁺ (bottom panel) are presented. *P < .05; ***P < .001.