The results of our cell invasion assay confirmed the results of our gel zymography assay, which partly prove that CD147 upregulation on macrophages may increase MMP production through both autocrine and paracrine stimulation and that macrophages may act as an amplifier of the pathogenetic cascade in RA via an increase in MMP production by interacting macrophages and fibroblasts. The gene discussed is BSG; the disease is rheumatoid arthritis.