In vitro studies of antiphospholipid antibodies and its cofactor, p2-glycoprotein I, show negligible effects on endothelial cell mediated protein C activation - Oosting, JD; Derksen, RHWM; Hackeng, TM; Van Vliet, M; Preissner, KT; Bouma, BN; De Groot, PG (Thromb Haemostas, 1991)