MMP2 and rheumatoid arthritis: Similarly, Song et al. have shown elevated expression level of lncRNAs called Hotair in PBMC and serum exosome, suggesting that lncRNAs could be used as potential biomarkers for diagnosing RA [29], while overexpression of Hotair by introduction of lentiviral construct results in decreased expression of MMP-2 and MMP-13 in FLS from RA patients.