Verification of plasma protein S-C4BP in factor V_Leiden plasma by Superose-6 size-exclusion chromatography. (A) Superose-6 size-exclusion chromatography of factor V_Leiden plasma: protein S was measured with a protein S ELISA (▲) and with a protein S-C4BP complex (△)ELISA. (B) Superose-6 size-exclusion chromatography of factor V_Leiden plasma saturated with C4BP: protein S was measured with a protein S ELISA (▲) and with a protein S-C4BP complex (△)ELISA. V_o: void column volume; V_t: total column volume.