Microarray analysis and validation. (A) Differential gene expression of cord blood CD34⁺ cells (n = 4) in response to SDF-1 (100 ng/mL) was analyzed by Affymetrix HG-U133 Plus 2.0 GeneChip software. Hierarchical analysis of the SDF-1–modulated genes involved in cell motility (left panel) and cell adhesion (right panel) were performed using the Euclidean distance metric. The color scale represents log₂ normalized signal intensity. CTRL, control. (B) Differential expression of 18 SDF-1–induced genes was validated by qPCR in CD34⁺ cells derived from the same cord blood samples used in microarray experiments (n = 4) plus CD34⁺ cells from an independent cohort of cord blood (n = 4-6). Gene expression levels were calculated by the comparative C_T method and are represented as the fold change of gene expression level in SDF-1–treated cells compared with control untreated cells. The red dashed line represents the 1.5-fold cutoff. Results are depicted as means ± SEM.