STAT1 and rheumatoid arthritis: RA fibroblast-like synoviocytes (RA-FLSs) treated with IL-27 induced the activation of STAT1 and increased the surface expression of intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, IL-6, CCL2, CXCL9, CXCL10, and matrix metalloproteinase-1 (MMP-1).