The plasmids pCB-BDD-FVIII, pCB-HC-INT, pCB-HC-INT+pCB-LC-INT (1:1), pCB-HC-N6-INT, pCB-HC-N6-INT+pCB-LC-INT (1:1), pCB-LC-INT, and mock control were transfected into 293 cells and assayed 48 hours after transfection. The secreted factor VIII (FVIII) HC was measured by enzyme-linked immunosorbent assay. The y-axes show the concentration of FVIII HC in ng/ml. Transfections were performed in quadruplicate to obtain average values. The SD is shown in the figure. BDD-FVIII, B-domain-deleted FVIII; INT, intein sequence.