AAPP inhibits GPVI-mediated platelet adhesion to collagen types I, III, but not type IV. Different types of collagen (types I, III, and IV) were coated in 96-well plates. The indicated concentrations of rAAPP were added to each well and incubated for 1 hour. After washing, GPVI-expressing Jurkat cells were allowed to adhere to each well for 1 hour. After washing, adhesion cells were quantified fluorometrically. The top box indicates the concentration of rAAPP (μg/mL). Results are representative of 3 independent experiments and expressed as the mean of triplicate reading plus or minus SEM for the indicated concentrations.