Konttinen et al. had previously used conventional reverse-transcriptase PCR to profile the expression of 16 MMPs in synovium (MMP1–3, MMP7-17 and MMP19), with induction of MMP1, MMP9, MMP13, MMP14 and MMP15 in synovium from rheumatoid arthritis compared with trauma controls [31]. This evidence concerns the gene MMP9 and rheumatoid arthritis.