VWF96 proteolysis by MDTCS in the presence and absence of mAbs. After preincubation of MDTCS_(6xHis) with no mAb (orange; n = 3); the noninhibitory, nonactivating anti-Spacer domain mAb 15D1 (light green; n = 3); the activating anti-Spacer domain mAb 3E4 (red; n = 3); or the activating anti-CUB1 domain mAb 17G2 (blue; n = 3), VWF96 (0.5 μM) was added to initiate the reaction. Reaction subsamples, stopped between 0 and 90 minutes, were analyzed by ELISA. Fitted time course data show the percentage of VWF96 proteolysis as a function of time (mean ± standard error of the mean).