Genes involved in normal developmental processes often have a role in tumour progression. Epithelial-mesenchymal transition (EMT) is a general phenomenon that is an essential event in embryonic development, tissue remodelling and wound repair. Genes that regulate EMT are attracting significant attention as mediators of tumour progression. Indeed, EMT is considered an important event during the evolution of malignant tumours and their progression to metastasis, with several reports of molecules involved in this process facilitating migration and invasion of epithelial tumour cells. Recent work linking the zinc transporter LIV-1 with the transcription factors STAT3 and Snail in zebrafish embryogenesis, throws new light on this transition and has important implications for the development of cancer.