Similar to the results in the monocytes/macrophages from RA patients, the density of total MMP-9 in undifferentiated THP-1 (1,128 ± 106) and differentiated THP-1 (THP-1, 2,988 ± 210) cells with CypA stimulation was higher than that in the control group (434 ± 60 in undifferentiated THP-1, 1,245 ± 116 in differentiated THP-1; P <0.001), and was markedly reduced by adding sdAbA1 (415 ± 61 in undifferentiated THP-1, 1,199 ± 133 in differentiated THP-1; P <0.001) or CsA (403 ± 57 in undifferentiated THP-1, 1,208 ± 125 in differentiated THP-1; P <0.001) (Figure 5B). Here, PPIA is linked to rheumatoid arthritis.