Our study first identified an increased expression of CXCR4 and CXCL12 mRNA and protein under a stimulation with MSU crystals in human U937 macrophages and also a higher level of serum CXCL12 in the gout patients compared with the controls, although the serum CXCR4 level was similar between the two groups. The gene discussed is CXCL12; the disease is gout.