CTRP-1 blocks intact VWF, VWF A1 domain, and VWF A3 domain binding to fibrillar collagen types I and III under static conditions. Plates were coated with collagen type I (▦) or III (▪) and were incubated with vehicle control or CTRP-1 alone, or the indicated mixtures of CTRP-1 with intact VWF (A), VWF A1 domain (B), or VWF A3 domain (C). Each bar represents the mean ± SD of 6 separate measurements. Differences were significant comparing vehicle and VWF alone (*P < .001), A1 domain alone (*P < .001), or A3 domain alone (*P < .02) by an unpaired, 2-tailed Student t test. Differences were significant (**P < .001) relative to incubation with vehicle alone by analysis of variance (ANOVA). OD indicates optical density.