Expression of representative genes assessed by quantitative RT-PCR. Comparison of the relative expression levels obtained from RT-PCR and cDNA microarray experiments for 5 genes present in the “poor risk” signature from CD34⁺ marrow cells from patients with MDS and healthy persons. Demonstrated are the similar degrees of expression for these genes using both analytic methods, as related to the reference standard (mean ± SEM in log₂ scale). Also shown are the differing levels of expression of these genes in tMDS (n = 5, increased) versus sMDS (n = 4, decreased) patients, which are further decreased in healthy persons (n = 4).