Genes differentially expressed at diagnosis and relapse in B-precursor ALL. (A) Heatmap of top 126 probe sets (48 high at diagnosis, 78 high at relapse; FDR < 10%). (B) Quantitative real time–PCR (qRT-PCR) validation of selected targets on independent samples (29 initial diagnosis, 19 relapse). The y-axis represents normalized ΔCT values (CT of gene of interest – CT of housekeeping gene). A high ΔCT signifies low expression, and vice versa. CT indicates threshold cycles for amplification. *SCGF was not expressed in 2 of the diagnosis samples; thus, an arbitrary CT value of 40 was used. Median expression is indicated by the horizontal bars.