Double immunofluorescence staining of RA synovium revealed that synoviolin+ fibroblast-like synoviocytes (FLSs) (Figure 2B, upper panel) and CD68+ macrophage-like synoviocytes, located in the hyperplastic lining cell layer (Figure 2B, lower panel), expressed IL-26. This evidence concerns the gene IL26 and rheumatoid arthritis.