Rheumatoid arthritis (RA) is a progressive autoimmune disease characterized by synovial hyperplasia and local inflammatory cell infiltration, 1,2 which eventually leads to cartilage destruction, bone erosion, and joint dysfunction. 3,4 Although the pathogenesis of RA remains to be elucidated, fibroblast-like synoviocytes (FLSs) are the effector cells of RA and play a crucial role in the inflammatory process. [5][6][7] In the inflammatory process of RA, FLS acquires the ability of excessive proliferation, secretion of pro-inflammatory cytokines, migration, and invasion, which can further aggravate RA. 8,9 However, current therapeutic strategies and drugs cannot target the activated FLS. 10 Therefore, clarifying the underlying mechanisms of abnormally activated FLS will help to explore novel therapeutic targets and approaches in RA.Dual-specificity phosphatase 5 (DUSP5), a member of the DUSP subfamily, can directly dephosphorylate extracellular signal-regulated kinases 1 and 2 (hereinafter referred to as ERK) 11 and is an intrinsic negative regulator of ERK. 12 It has been implicated as a major modulator of critical signaling pathways in several diseases. Previous studies confirmed that DUSP5 is a direct target gene of p53 and has tumor-suppressive functions in several types of cancer. 13,14 Recently,