In the presence of pro-inflammatory factors such as IL-6, the increase in the SOX5 mRNA expression level promotes the migration and invasive properties of human FLSs by regulating RANKL and MMP9 mRNA expression levels, which may cause ECM invasion, leading to joint destruction in patients with rheumatoid arthritis (RA) [123,124]. This evidence concerns the gene MMP9 and rheumatoid arthritis.