Since FLS expressed CCR9 in the RA synovial tissues, we examined the stimulatory effects of CCL25 on the cultured RA FLS, which also expressed CCR9 (Figure 2A; mean fluorescence intensity (MFI) for CCR9: 157,963 ± 37,811, MFI for isotype control: 70,914 ± 3,163 (mean ± standard error of the mean (SEM)), n =3). Here, CCR9 is linked to rheumatoid arthritis.