PF4 and rheumatoid arthritis: However, expression of both CXCL4 and CXCL7 was significantly elevated in patients with early RA compared with patients with resolving arthritis (CXCL4 and CXCL7; p<0.05) and patients with established RA (CXCL4 and CXCL7; p<0.05; figure 3C), which supported the findings made at the mRNA level.