However, the other study indicated that MMP-2 suppresses RA synovial fibroblast-mediated cartilage degradation; MMP-2 KO mice developed arthritis of greater clinical and histological severity than wild-type mice (46). Therefore, the role of MMP2 in the progression of RA-FLS is still controversial. We speculate that the varied roles of MMP2 in the progression of RA may be associated with the inconsistency of microenvironment and experimental conditions. This evidence concerns the gene MMP2 and arthritic joint disease.