Sphingosine 1‐phosphate/sphingosine 1‐phosphate receptor 1 signaling in rheumatoid synovium: Regulation of synovial proliferation and inflammatory gene expression

These findings suggest that S1P signaling via S1P receptors plays an important role in cell proliferation and inflammatory cytokine-induced COX-2 expression and PGE2 production by RA synoviocytes. Thus, regulation of S1P/S1P1 signaling may represent a novel therapeutic target in RA.