Studies have found that the P-glycoprotein (P-gp) encoded by the ABCB1 gene is involved in the transport of cytokines (e.g., IL-2, IL-4, IFN-γ, TNF-α), and its decreased function may lead to the accumulation of proinflammatory cytokines, thereby exacerbating RA inflammation (11). The gene discussed is ABCB1; the disease is rheumatoid arthritis.