Gene expression patterns in the subset of patients harboring BCR/ABL (A) Agglomerative hierarchical clustering according to similarity in gene expression patterns. The variation in expression is displayed for the 500 clones (463 genes) for which the log₂ intensity ratio differed by at least 1.5 from its mean on at least 2 arrays. The broad features of the clustering patterns were robust to variations in gene selection criteria. (B) SAM identifies genes whose expression is statistically different in the 2 groups of BCR/ABL samples (338 clones representing 314 genes, 1000 permutations, median false significant clones = 2.8), (C) selected genes identified by SAM.