ARG1 and rheumatoid arthritis: At the level of molecular regulation, SIN promotes RA-FLS apoptosis by up-regulating microRNA-23b-3p and fibroblast growth factor 9 (FGF9) and balances the expression of pro-inflammatory factors (TNF-α, IL-1β) and anti-inflammatory factors (arginase 1 (Arg-1), IL-10) with the help of nuclear factor kappa-B (NF-κB) pathway (Yi et al., 2021; Shang et al., 2023).