In 2001, we reported the establishment and use of a three-dimensional (3D) culture model for breast aciniar organogenesis using a human mammary epithelial cell line MCF-10A (Nat Cell Biol. 2001, 9:785-92). In 2015, we reported the established of 3D models for human exocrine pancreas organogenesis and to grow patient-derived primary tumor cells as tumor organoids (Nat. Med. 2015, 11:1364-71). We use these organoid models to understand new mechanisms regulating normal morphogenesis, tumor cell biology and discover new therapeutic strategies.