When RNA from SF PMN obtained from RA patient nos 1, 2, 7 and 8 and healthy donor no. 2 was used, semiquantitative RT-PCR (Figure 3b) revealed an upregulation of two selected chemokine receptors, CCRL2 and CXCR4, in SF PMN, thereby confirming the results of the microarray analysis. The gene discussed is CXCR4; the disease is rheumatoid arthritis.