MINK1^−/− platelets show impaired aggregation responses associated with defective release of ATP. (A-D) Platelets were stimulated with collagen, thrombin, the TXA₂ analog U46619, and ADP (in the presence of fibrinogen). Aggregation and ATP release was assessed with a Chrono-log lumiaggregometer under stirring at 1200 rpm for 5 minutes. Traces are representative of at least 3 independent experiments. (E) Platelets were then fixed with 1.5% paraformaldehyde for 30 minutes at room temperature, and observed by differential interference contrast (Nikon TE-2000S, ×10 objective, DS-2MBWc-U1 CCD camera). Data are representative of 3 independent experiments.