SLC39A8 and rheumatoid arthritis: In RA synoviocytes, the presence of TNF-α alone was not sufficient to enhance ZIP-8 expression (Fig 2A, control 1.08 ± 0.40 vs. TNF-α alone 2.43 ± 0.57) but the combination of IL-17 and TNF-α enhanced ZIP-8 expression synergistically (Fig 2A, control: 1.08 ± 0.40 vs. combination of IL-17 and TNF-α: 4.38 ± 1.35; p<0.05) (S2 Table).