We observed CYLD expression in the lining and sublining layers of RA synovium, with intense staining found in the endochylema as well as the nuclei of lining cells (both macrophage-like synoviocytes and FLSs) and sublining of inflammatory cells, implying that CYLD was expressed in RA-FLSs. The gene discussed is CYLD; the disease is rheumatoid arthritis.