Myr-Arf6 peptide inhibits F-actin formation. Washed platelets were treated with DMSO (A) or 25 μM myr-Arf6 (B), myr-Arf1 (C), or nonmyr-Arf6 (D) peptides for 5 minutes at 37°C. After washing, the platelets were allowed to bind to collagen-coated coverslips for 10 minutes at 37°C, fixed with 3.7% formaldehyde, and quenched with 50 mM NH₄Cl. TRITC-conjugated phalloidin in 10% FBS/PBS with 0.2% saponin was used to stain for F-actin. Images were taken using a SPOT CCD camera, model 9.0 monochrome-6 (Diagnostic Instruments, Sterling Heights, MI) and processed using SPOT Advanced software, version 4.1.1 (Diagnostic Instruments). Only contrast and brightness were adjusted with Photoshop 7.0 software (Adobe, San Jose, CA).