SIRT6 and rheumatoid arthritis: The sirt6 expression in RA-FLSs after transfection (Fig. 5a-c) revealed that the mRNA expression and protein levels of sirt6 were higher in the oe-sirt6 group than the oe-sirt6-NC group (p < 0.05), however the mRNA and protein levels were lower in the sh-sirt6 group when compared to the sh-sirt6-NC group (p < 0.05).