DAPP1 is tyrosine phosphorylated in response to human and mouse platelet activation. (A) Western blotting of DAPP1 immunoprecipitates (IP) with the 4G10 antibody after thrombin (0.2 U/mL) or CRP (5 µg/mL) stimulation of human platelets for 5 minutes, after 10 minutes of preincubation with either Veh, WTM (100 nM), PP1 (10 µM), AR-C66096 (ARC, 1 µM) or Abciximab (Abcx, 1 μg/mL). The arrow indicates the position of tyrosine phosphorylated (pY) DAPP1. Corresponding whole-cell lysates were blotted for total AKT to confirm input loading and for AKT phosphorylation and global tyrosine phosphorylation to confirm the action of the agonists and inhibitors. (B) Western blotting of DAPP1 immunoprecipitates after treatment of human platelets for 5 minutes with the platelet primers, thrombopoietin (200 ng/mL), insulin-like growth factor-1 (200 nM), or the agonists described in panel A. (C) DAPP1 immunoprecipitates from mouse platelets stimulated for 5 minutes with CRP (10 μg/mL) or thrombin (αT, 0.5 U/mL) were blotted for 4G10 (pY) and DAPP1. (D) DAPP1 expression in wild-type (WT) and DAPP1^−/− (KO) mouse platelets. Results are representative of at least 3 independent experiments.