Retention of mutant rVWF in the ER and delay in pseudo-WPB formation. HEK293 cells were transiently transfected with WT rVWF (A) or mutated rVWF (Cys1225Gly, panel B; Cys788Arg, panel C; Arg 273Trp, panel D) and immunolabeled for VWF and calreticulin at different times after transfection. At each time point, 50 cells were observed, and the percentage of cells was plotted according to the VWF subcellular localization (Figure 1). Each bar represents the mean ± standard deviation of 4 independent experiments.