Figure 1. Hierarchical clustering of 115 breast tumor tissues and 7 non-malignant tissues using the "intrinsic" gene set. A. A scaled down representation of the entire cluster of 540 genes and 122 tissue samples based on similarities in gene expression. B. Experimental dendrogram showing the clustering of the tumors into five subgroups. Branches corresponding to tumors with low correlation to any subtype are indicated in gray. C. Gene cluster showing the ERBB2 oncogene and other co-expressed genes. D. Gene cluster associated with luminal subtype B. E. Gene cluster associated with the basal subtype. F. A gene cluster relevant for the normal breast-like group. G. Cluster of genes including the estrogen receptor (ESR1) highly expressed in luminal subtype A tumors. Scale bar represents fold change for any given gene relative to the median level of expression across all samples. (See also Figure 6, which is published as supporting information).