Epithelial-mesenchymal transition (EMT) plays a central role in both physiological and pathological settings including embryogenesis, wound healing, stem cell transformation and tumor metastasis.During EMT, the epithelial cells lose cell-cell interaction, switch gene expression from epithelial to mesenchymal profiles and gain motility and invasiveness.In cancer, EMT plays a critical role in initiating epithelial cancer metastasis by not only disrupting the epithelial integrity but also promoting the intravasation step of metastasis.Our recent studies demonstrate that in breast cancer a number of MMPs are involved in these processes and the expression and/or activity of the MMPs are controlled by the EMT-inducing transcription factor KLF8.