Expression profile of TAL1-direct targets in primary T-ALL samples. (A) Microarray fluorescence intensities corresponding to the expression of TAL1 and RALDH2 genes in T-ALL samples. High levels of expression of RALDH2 were detected in all TAL1-positive cases, in agreement with a role of TAL1 in the activation of this direct target gene. Cases were arranged on the basis of the expression of T-ALL oncogenes, including HOX11, HOX11L2, and TAL1. TAL1-like cases denote samples with high levels of RALDH2 similar to those present in TAL1-positive samples, but lacking TAL1 expression. (B) Heat map representing relative expression levels of TAL1 and TAL1 direct target genes in HOX11/HOX11L2-positive cases and TAL1-positive samples. Each column represents 1 of 26 samples positive for HOX11, HOX11L2, or TAL1 by RT-PCR, while each shows the expression pattern of a particular gene identified as a TAL target by ChIP on chip. Relative expression levels are normalized across the samples; levels greater than or less than the mean are shown in shades of red or blue, respectively.