CXCL8 and rheumatoid arthritis: Interestingly, pre-treatment of RA-FLS with a p38/MAPK inhibitor (SB 202190, 100 μmol/L) inhibited CRP-induced RA-FLS invasion (Figure 6C) as well as induction of MMP9 without significant alternation of CXCL8, CCL2, and IL-6 expression (Figure 6B).