Given the presence of citrullinated fibronectin in rheumatoid arthritis, the paucity of information about citrullinated fibronectin, and the importance of the interactions of fibronectin and synovial fibroblasts in rheumatoid arthritis, we decided to investigate how citrullinated fibronectin modulates synovial fibroblast behavior. The gene discussed is FN1; the disease is rheumatoid arthritis.