Representative picture showing that expression of intracellular and total citrullinated protein (CP), as well as PAD2 and PAD4 enzymes, is higher in rheumatoid arthritis (RA; upper panel) as compared with healthy (lower panel) synovial tissue. Frozen synovial biopsy sections show diaminobenzidine (brown) immunoperoxidase staining (hematoxylin counterstained) for citrullinated proteins and peptidylarginine deiminase (PAD) enzymes detected with the F95 antibody, anti-PAD2 (with two different antibodies, ROI002 and SN665), and PAD4 (with two different antibodies, SN823 and SG1467) antibodies (original magnification, ×100). Insets show close-up details from the same samples.
Makrygiannakis et al. Arthritis Research & Therapy 2012 14:R20 doi:10.1186/ar3702