Multimer analysis following rVWF expression. HEK293 cells were transiently transfected with WT and mutant rVWFs. Samples of cell lysate (A) and media (B) were prepared as described in “Materials and methods” and were electrophoresed in 1.5% agarose/0.1% SDS gels under nonreducing conditions. Multimers were visualized by means of a polyclonal rabbit antihuman VWF serum and alkaline phosphatase-conjugated swine antirabbit immunoglobulins.