When RA FLS were incubated with IL-17 and TNF-α, mRNA expression of HIF-2α was synergistically elevated in IL-17/TNF-α-treated cells (0.035 ± 0.006) compared unstimulated control FLS (0.137 ± 0.036) (n = 6; Figure 4A,B). Here, EPAS1 is linked to rheumatoid arthritis.