TLR4 and rheumatoid arthritis: We investigated the effect on FLS of cytokines commonly presented in the inflammatory joints of patients with RA, including tumor necrosis factor‐alpha (TNF‐α), IFN‐γ, interleukin (IL)‐6, IL‐1β, IL‐17A, IL‐4, transforming growth factor‐beta (TGF‐β), and Toll‐like receptor 4 (TLR4) ligand (lipopolysaccharide, LPS).