SLC39A1 and rheumatoid arthritis: The present study showed that, as in RA patients38, zinc levels were locally increased in the synovial fluid and synovial tissues of CIA mice and that among all the examined zinc importers (ZIP1–ZIP14) and exporters (ZNT1–ZNT10), ZIP8 was specifically upregulated in the synovial tissues of inflamed joints in CIA mice and RA patients.