In the context of RA, the effects of JAK-STAT signalling include but are not limited to production of the chemokine IL-10 by collagen-stimulated B cells [63] which inhibits neutrophil recruitment [64] and IL-9 production by Th-9 cells, prolonging the survival of neutrophils in synovial fluid and increasing MMP-9 production [65,66]. Here, MMP9 is linked to rheumatoid arthritis.