In vitro assays have confirmed that expression of POSTN and TWIST1 are elevated in fibroblast-like synoviocytes (FLSs) of rheumatoid arthritis patients (RA-FLSs) and are crucial for the migration and invasion of FLSs stimulated with interleukin (IL)-1β [38]. The gene discussed is TWIST1; the disease is rheumatoid arthritis.