This document discusses epithelial-mesenchymal transition (EMT) and its role in cancer metastasis. It summarizes findings from a study using a triple-transgenic mouse model of breast cancer metastasis that found: 1) Primary tumor cells disseminated and formed metastases while maintaining their epithelial phenotype, not undergoing EMT. 2) Inhibiting EMT with miR-200 had no effect on metastasis. 3) Non-EMT tumor cells were sensitive to chemotherapy, whereas mesenchymal cells were resistant. The study provides evidence that EMT may not be required for cancer metastasis in this model.