Extending the investigation of STAT1 and STAT3 cytokine signalling to wild‐type, Il6−/− and Il27ra−/− mice with antigen‐induced arthritis, studies show that these mice develop joint disease resembling the heterogeneous features of synovitis commonly seen in humans with rheumatoid arthritis [93, 100, 184, 199, 207, 208]. Here, STAT3 is linked to synovitis.