Figure 4

Supervised classification of ER+ and ER- ERBB2 -amplified BCs based on RNA expression data. Left, classification of 51 samples using a 638-gene expression signature (listed in Additionnal file 1-Table S7C). Top panel, matrix of expression data. Each row of the data matrix represents a gene and each column represents a sample. Expression levels are depicted according to the color scale shown at the bottom. Red and green indicate expression levels respectively above and below the median. The magnitude of deviation from the median is represented by the color saturation. Genes are ordered from top to bottom by their decreasing signal-to-noise ratio. Tumor samples are ordered from left to right according to the decreasing correlation coefficient of their expression profile with the median profile of the ER+ samples (Bottom panel). The orange line indicates the threshold 0 that separates the two predicted classes of samples, "ER+ class" (to the left) and "ER- class" (to the right). The middle panel indicates the observed ER status of tumors (black square, ER+; white square, ER-). Right, correlation between the molecular grouping based on the combined expression of the 638 genes (predicted status) and the observed ER status of samples.