Effect of myr-RGT on fibrin clot retraction and platelet aggregation. (A) Washed platelets were resuspended in HEPES buffer and incubated with different peptides or their vehicles as indicated. Then 2 mg/mL of human fibrinogen was added and fibrin clot formation was initiated by adding 1 U/mL of thrombin. Clot retraction was monitored over time, and photographs of the clots were taken at different time points (bottom panel). Peptide concentrations: *62.5 μM; **125 μM; ***250 μM. The histograms of the clot size were generated from the photographs by calculating the ratio of the surface area of the retracted clot versus that of the initial clot. (B) Aggregation of nontreated or peptide-treated platelets was induced in an aggregometer at 37°C under constant stirring (1000 rpm) by ADP (2 μM), ristocetin (1.25 mg/mL) in PRP, or by thrombin (0.1 U/mL) in washed platelets preincubated with (A) DMSO, (B) myristic acid and RGT peptide at a concentration of 250 μM, (C) scrambled myr-GRT at 250 μM, myr-RGT at concentrations of (D) 62.5 μM, (E) 125 μM, and (F) 250 μM, respectively. (Inset) Platelets in plasma treated with 250 μM of (F) myr-RGT, (C) scrambled myr-GRT, or (A) vehicle DMSO were stimulated by TRAP (10 μM) to aggregate.