1. From the Unit of Thrombosis and Hemostasis, Department of Hematology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain (J.C.S., M.B., M.G., E.M., J.M., J.F.); the Department of Genetics, Southwest Foundation for Biomedical Research, San Antonio, Tex (L.A., J.B.); and the Department of Biology, Trinity University, San Antonio, Tex (W.H.S.).