PADI4 and rheumatoid arthritis: PAD2 and PAD4 expression was detected in all baseline RA samples (100%) and a vast majority of the healthy synovial biopsies (seven of eight, 87.5% positive for ROI002 antibody; six of eight, 75% positive for SN665 antibody; all eight, 100% positive for SG1467 antibody, and seven of eight, 87.5% positive for SN8233 antibody) and with a general higher expression of all investigated molecules in RA as compared with healthy synovium (Figure 1; P < 0.05 for all investigated antibodies).