Cumulative production of vWF released into the supernatant from cultured HUVEC exposed to fluid shear stress (8 dynes/cm2 ) for 6 and 15 hours (n = 6 and 5, respectively). Data are expressed as the mean ± SE of vWF released from cells exposed to shear and to static condition (A) and as the percentage increase of cumulative production by cells exposed to flow versus static controls (B). *P < .05 flow versus static; **P < .01 flow versus static; °P < .05 static at 15 hours versus static at 6 hours.