Jane Visvader is a leading Australian molecular and cellular biologist who has greatly clarified breast development and the role of stem cell biology in breast cancer. In a remarkable discovery, her team identified and isolated the stem cell that generates the entire breast. Her work also defined the cellular hierarchy within the breast, identified master regulators that orchestrate its differentiation program, and discovered that certain types of breast cancer originate from specific progenitor cells. The results of her research have profound implications for understanding the cellular origins of both normal and cancerous epithelial tissues.