BCL-2 expression in malignant human T-cells. (A) Differential gene expression profiling of primary immature T-ALLs vs T-ALLs from other subgroups (log₂[fold change] > 2; P < .05). A heat map of the top 50 differentially expressed genes is shown. Genes in the heat map are shown in rows and each individual leukemia sample is shown in 1 column. Expression levels are visualized as color-coded differential expression from the mean in standard deviation units with red indicating higher levels and blue lower levels of expression. This primary T-ALL cohort has previously been investigated²¹  and hierarchical clustering was used to define molecular-genetic subtypes of human T-ALL, as previously described.⁶  (B) BCL-2 expression levels (probe 203685_at) in an independent cohort of 117 human T-ALL samples. Molecular-genetic subtypes of human T-ALL have been defined as previously described.⁵  nBM, normal bone marrow. P = 0.0051.