Considering that mRNA levels of Notch receptors are frequently not representative of the protein levels of N1-ICD, activated Notch1 pathway status in this cohort was inferred from expression levels of a Notch-dependent gene signature, built up by selecting published Notch1 targets, for which Notch responsiveness and/or direct promoter binding as well as their expression in breast cancer was demonstrated (Notch direct target gene signature, NDT, supplementary Table S2). This evidence concerns the gene NOTCH1 and breast carcinoma.