Hematoxylin and eosin (HE) staining showed that the RA group exhibited obvious synovial hyperplasia, increased cell infiltration, and higher synovitis scores than the control (Fig. 1c and Fig. S2A), which was consistent with an increase in FABP4 expression in mice with AIA (Fig. 1c and Fig. S2B). The gene discussed is FABP4; the disease is rheumatoid arthritis.