Versican and CCL2 mRNA levels in monocytes from patients with systemic sclerosis and healthy controls. Quantitative PCR analysis. Relative mRNA expression levels were calculated as a ratio of mRNA levels of the genes of interest to those of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Bars in the graph denote the mean. Differences between the groups were analyzed by Mann-Whitney U test. SSc, systemic sclerosis.