In this study, during investigating the role of DHA on abnormal proliferation of synovial cells, we found that DHA treatment induces apoptosis in human synovial cells from patients with RA (RA-FLS, both in MH7A cells and primary RA-FLS) through induction of ROS, CHOP, and DR5, suggesting that CHOP functions as a pro-apoptotic factor. This evidence concerns the gene DDIT3 and rheumatoid arthritis.