The effect of the A4 on intact platelets. (A) The A4 peptide decreases filamin A binding to GpIbα. (B) Lysates from the same samples after they were subjected to immunoblotting for tyrosine phosphorylated proteins. (C) Quantitative evidence that delivery of the A4 peptide decreases the tyrosine phosphorylation of FAK, α-actinin, Syk, Fyn, and Src when platelets are sheared at 120 dyne/cm² (n = 3; bars present means + SDs; *P ≤ .05; **P ≤ .01 when compared to sheared untreated platelets by the Student t test).