Finally, we found the mesenchymal marker, SMA, present at higher levels in MECs extracted from TAp63−/− compared with WT mammary glands (Figure 3n), in agreement with previous data showing the association of EMT with an acquisition of early TIC characteristics.20, 21 We further demonstrated that TAp63−/− mammary adenocarcinomas express the luminal marker NKCC1, are ER positive and lose expression of the polarity protein, Scrib (Supplementary Figures S3a–c). Here, SMN1 is linked to breast adenocarcinoma.