CYLD and rheumatoid arthritis: Via RT-PCR we found that expression of CYLD mRNA in RA-FLSs was significantly lower than in OA-FLS controls (Fig. 2B; 0.41 ± 0.43 vs. 1.23 ± 0.84; P < 0.01), and via IF staining we also found that expression of CYLD in RA-FLSs was obviously lower than in OA-FLSs (Fig. 2C).