Expression studies demonstrating increased intracellular retention for rVWF protein containing the Tyr1584Cys mutation. Secretion of rVWF protein from COS-7 cells transfected with the pCIneoC1584 construct or cotransfected with wild-type and mutant constructs (heterozygous state) was decreased by 38% (P = .005) and 16% (P = .07), respectively, relative to the secretion of wild-type rVWF protein and the intracellular levels of rVWF were increased by 47% (P = .04) and 8% (P = .6), respectively. n = 4-6. ▦ indicates media; □, lysate. Error bars indicate SEM.