Figure 2

The CPC genes yield consistent, subtype-specific PCs in gene expression data sets. In each panel, PCA was performed separately on each data set using only the CPC genes, and the resulting first and second PCs from each data set were compared by hierarchical clustering. (a) The first two PCs of the 108 CPC genes in the DNBC subset of four validation data sets. (b) The first two PCs of the 108 CPC genes in the DNBC subset (black) and the ER-positive HER2-negative subset (red) of the four validation data sets.