Figure 1. Microarray analysis of chemokine and chemokine receptor expression in the rheumatoid arthritis (RA) and non-RA synovia. A pair of human cytokine array membranes were hybridized to 33P-labelled cDNA probes prepared from pools of (a) RA mRNA (n = 8) and (b) non-RA mRNA (n = 9). The membranes were washed and autoradiographed. (c) The position of the 33 chemokines (C), the 16 chemokine receptors (CR), the nine positive control 'housekeeping genes' (HKG) and the six negative controls (NC). Each gene was printed in duplicate. The star indicates the position of the genes CXCR1, CXCR2, CXCR4 and CXCR5 (reading top to bottom) and shows their differential expression in RA and non-RA synovia. Exposure time was 7 days and 14 days for (a) and (b), respectively.