A study by researchers at Tufts University School of Medicine, the Sackler School of Graduate Biomedical Sciences at Tufts, and Tufts Medical Center improves our current understanding of the origins of breast cancer. The researchers propose a new model for breast cell differentiation that identifies two populations of progenitor cells, one of which appears to be the cell of origin for luminal-like breast cancer, the most common form of the disease. The study, published in the January 19 issue of Cancer Cell, identifies a possible target for breast cancer drugs.