Correlation between MMP-9 gene expression and the percentage of marrow cellularity in MDS patients. Gene expression data obtained from CD14⁺ cells at time 0 (top panel), and after 5 days of culture in control medium (middle panel) or HS5 CM (bottom panel) were analyzed with respect to marrow cellularity in 27 patients with MDS. MMP-9 gene expression was determined by the real-time PCR assay and normalized with G3PDH gene expression (y-axis). The x-axis shows the percentage of marrow cellularity. Regression analysis indicates a significant negative correlation with cellularity for HS5 CM inducible MMP-9 expression in the bottom panel (R = −0.62; P < .001), but not for time 0 expression (R = 0.15; P = .42) or control medium expression (R = −0.21; P = .30) in the top and middle panels, respectively.