Knockdown of HtrA2 inhibited the production of IL1β-, TNFα-, or LPS-stimulated proinflammatory cytokines (IL-6 and IL-8) by RA FLSs without causing cell death, as determined by the MTT viability assay (Fig. 5B, C and Supplementary Fig. 2). The gene discussed is CXCL8; the disease is rheumatoid arthritis.