W7 causes the dissociation of calmodulin from its GPVI interaction site. Aliquots of purified calmodulin (10 μM) were passed over a surface plasmon resonance sensor chip containing immobilized biotinylated peptide with sequence matching the calmodulin-binding region of GPVI cytoplasmic tail, as described in “Materials and methods.” The association of calmodulin in HEPES-buffered saline containing 1 mM CaCl₂ (trace A) or the same buffer containing 10 mM EDTA (trace B) or calmodulin that had been mixed with 150 μM W-7 prior to passage across the chip (trace C) was measured by surface plasmon resonance.