In previous studies, DcR3 [14], TL1A [15], and FasL [16] regulation of gene expression in RA-FLS, as demonstrated using cDNA microarrays, suggest that DcR3 signaling, as well as that of its two ligands, TL1A and FasL, is involved in RA pathogenesis. The gene discussed is TNFSF15; the disease is rheumatoid arthritis.