Expression modules in the SCGS. Four distinct expression modules (row clusters) are apparent within the stem cell genes. To demonstrate the transcriptome-wide implications of these profiles, this figure displays a series of cell types, ranging from fully differentiated (normal breast), through the associated malignancy, partially committed stem cells, and pluripotent stem cells. Each gene (row) has been independently z-score normalized to improve readability and highlight cluster-specific trends. Biological significance of each cluster was determined by GO analysis (Tables s5 to s8 in Additional file 1). The individual genes represented in each cluster can be found in Tables s1 to s4 in Additional file 1.