Expression of ADAMTS13 variants in combination with W7 located in the signal peptide. Conditioned medium (A) and cell lysate (B) of transfected HEK 293 cells expressing ADAMTS13 variants (abbreviations corresponding to Table 1) were normalized according to β-gal activity and subjected to immunoblot analysis using anti-ADAMTS13 antibody. The representative of at least 3 repetitive experiments is shown.