In the synovial fibroblasts of RA patients, the binding of exogenous ligands to TLR2 or TLR4 enhances the production of pro-inflammatory cytokines and chemokines, such as IL-6 (Tang et al., 2010), instigating cartilage inflammation and degeneration (Lorenz et al., 2013). The gene discussed is TLR4; the disease is rheumatoid arthritis.