Cell migration plays a pivotal role in many physiological and pathophysiological processes including embryogenesis, angiogenesis, immune defense, wound healing, or the formation of tumor metastases. Evidence is accumulating that ion channels and transporters is also required for optimal cell migration and a model is proposed that combines ion transport with cytoskeletal mechanisms of cell migration. However, the role of water transport in cell migration is underinvestigated. In the April 7, 2005 issue of Nature, Saadoun et al. discovered the importance of aquaporin-mediated transmembrane water flux in cell migration, angiogenesis and tumor growth, provided a new molecular mechanism of cell migration and opened a new field of aquaporin gene function and therapeutic application.