Figure 2. Hierarchical clustering of gene expression data from van't Veer et al. A. The entire cluster of 461 genes across 97 sporadic tumors. B.Experimental dendrogram showing the similarities between the tumor samples. Branches are color-coded according to the tumor subtype to which the corresponding tumor sample show the highest correlation. Tumors with low correlation (< 0.1) with a specific subtype are indicated by gray branches. C. Gene cluster associated with the luminal subtype A. D. Gene cluster containing the ERBB2 oncogene and co-clustered genes. E. Group of genes that tend to be highly expressed in luminal subtype B tumors. F. Gene cluster characteristic of basal tumors. Scale bar represents fold change for any given gene relative to the median level of expression across all samples. (See also Figure 7, which is published as supporting information).