FABP4 and rheumatoid arthritis: In consistent with the upregulation of leptinexpression in RA-FLSsafter 3-day adipogenic induction and under hypoxic conditions, the expression of adipogenic markers, C/EBPα, PPARγ, and FABP4 was also elevated, which indicated the increase of RA-FLS adipogenesis (Figures 5(a)–5(c)).