Representative images of two experiments showing shear stress-induced vWF release by immunofluorescence. Confluent HUVEC were maintained in static conditions (1a and 1b), subjected to shear stress of 8 dynes/cm2 for 6 hours (2a and 2b), or stimulated with IL-1β (100 U/mL) for 6 hours (3a and 3b). After fixation and permeabilization, the cells were stained by sequential incubation with rabbit anti-vWF antibodies and fluorescein-conjugated antirabbit IgG. The rod-shaped Weibel-Palade bodies are found in unstimulated controls, whereas cells exposed to flow and stimulated with IL-1β showed a depletion of Weibel-Palade bodies and the appearance of extracellular patches of staining.