We have shown that FXa stimulation of HUVEC is mediated via PAR-1 and PAR-2 dependent signalling and that this response is enhanced by IgG from FXa reactive antibody positive patients with APS as well as SLE/APS- and can be blocked by a specific FXa proteolytic inhibitor, antistasin, HCQ and fluvastatin. This evidence concerns the gene F10 and systemic lupus erythematosus.