Geoff Lindeman and his team identified the stem and progenitor cells that generate all ductal tissue in the breast, in both mice and humans. His laboratory was the first to identify the culprit progenitor cell responsible for breast cancer in BRCA1 mutation carriers. Discoveries from his group have provided a new framework for studying the molecular and cellular events that lead to breast cancer, with direct implications for the treatment and prevention of breast cancer. He has translated his group’s fundamental research findings into novel early phase clinical trials.