Multimeric analysis and expression levels of recombinant mutant VWF.VWF cDNAs encoding wt, p.L1696R, or p.P1824H mutants were transfected in COS-7 cells. Cotransfections (1:1) of the mutant with wt cDNA were also performed in COS-7 cells. VWF:Ag levels resulting from these different transfections were measured by enzyme-linked immunosorbent assay in both cell supernatants (A) and cell lysates (B) and are expressed as micrograms per milliliter. The ratio of VWF:Ag in lysates over supernatants (SN) is also represented (C). Data represent means ± SD of 3 independent experiments. *P values < .05 compared with wt values. The multimeric profile of the various recombinant proteins was analyzed through 2% sodium dodecyl sulfate-agarose gel electrophoresis (D).