SFK activation and adhesion to collagen is spared by acalabrutinib but not ibrutinib. Washed human platelets from healthy donors were preincubated with a range of (A) acalabrutinib or (B) ibrutinib and then stimulated with 1 µg/mL CRP-XL for 3 minutes at 37°C; tyrosine phosphorylation of Src (Y418) and Btk (Y223) were measured by western blot using site-specific antibodies and total levels of Tec tyrosine phosphorylation were measure by ELISA. Points represent mean levels of tyrosine phosphorylation relative to vehicle-treated controls ± SEM. (C) Representative images of phosphoblots. Washed platelets treated with a range of acalabrutinib, ibrutinib, or dasatinib concentrations and stimulated as previously and blotted for (D) tyrosine phosphorylation of Lyn (Y396) or (E) total phosphotyrosine using a site-specific antibody or 4G10, respectively. Points represent mean levels of tyrosine phosphorylation relative to vehicle-treated controls ± SEM. (F) Aggregation 1 µg/ml CRP-XL stimulated of washed platelets was performed in 96-well plates after treatment with a range of concentrations of acalabrutinib, ibrutinib, or dasatinib concentration response curves are mean platelet aggregation ± SEM relative to vehicle-treated control. (G) Acalabrutinib, ibrutinib, or dasatinib-treated washed platelets from healthy donors were allowed adhere to collagen-coated wells of a 96-well plate after 45 minutes at 37°C; graphs plot concentration response curves to mean numbers of adhered platelets ± SEM relative to vehicle treatment. (H) Representative images of phosphoblots for platelets treated with tyrosine kinase inhibitors.