Expression of endothelial protein C receptor (EPCR) in synovial tissues, synovial fluids, and cultured synovial fibroblasts (SFs). (A) EPCR expression in synovial tissues from patients with rheumatoid arthritis (RA) and osteoarthritis (OA), detected by immunohistochemistry, and counterstained with Hematoxylin and Scott’s Bluing Solution. Scale bar: 400 μm. (B) Soluble EPCR (sEPCR) in synovial fluids from patients with OA and RA, detected by enzyme-linked immunosorbent assay (ELISA) and expressed as mean ± standard deviation (SD) (n = 12 each). (C) Co-localization of EPCR with the fibroblast marker, ER-TR7, in synovial tissues from patients with RA and OA, detected by immunofluorescent staining. Scale bar: 50 μm. (D) EPCR expression in cultured SFs, detected by immunofluorescent staining. Scale bar: 20 μm. Nuclei were counterstained with 4′-6-diamidino-2-phenylindole (DAPI) (blue) in (C) and (D). The images represent one of three experiments. (E) EPCR in whole cell lysates of cultured SFs detected by ELISA and expressed as mean ± SD (n = 7 each). Data was analyzed by Student t test, **P <0.01.