FIGURE 2. Validation of pathway predictions in tumours.

a, Mouse mammary tumours derived from mice transgenic for the MMTV-MYC (five samples), MMTV-HRAS (three samples) or MMTV-HER2 (seven samples) oncogenes, tumours dependent on loss of Rb (six samples), or seven samples of normal mammary tissue were used to verify accuracy and specificity of our signatures. The predicted probability of Myc, E2F3 and Ras activity in mouse tumours was sorted from low (blue) to high (red), and displayed as a colour bar. b, Prediction of pathway status in mouse lung cancer model. A set of previously published mouse Affymetrix expression data comparing normal and tumour lung tissue with spontaneous activating KRAS mutations¹⁴ was used to validate the predictive capacity of the Ras pathway signature. The predicted probability of Ras activity in the normal and tumour tissue was sorted from low (blue) to high (red), and displayed as a colour bar. c, Relationship of Ras pathway status in NSCLC samples to cell type of tumour origin. The corresponding tumour cell type is indicated as either squamous (S) or adenocarcinoma (A). Ras mutation status is indicated by an asterisk.