Book excerpt: The identification of normal and breast cancer stem cells has offered a new vision of this heterogeneous disease and new hopes for its prognosis and treatment. This volume provides an overview of recent developments in mammary stem cell research and discusses the many varieties of approaches used by researchers to investigate the properties and functions of mammary stem cells. The beginning chapters provide readers with an introduction to mammary stem cells, and the processes used to characterize stem cells and isolate them via fluorescent activated cell sorting. The next few chapters discuss DNA and mRNA sequencing, proteomic techniques to help profile cells, lentiviral cell transduction for gene expression, and in vivo lineage tracing. The final few chapters are dedicated to following stem cells from their initial niche to the new microenvironment at their metastasis site, and to studying these cells using physical and mathematical approaches. Written in the highly successful Methods in Molecular Biology series format, the chapters include the kind of detailed description and implementation advice that is crucial for getting optimal results in the laboratory. Authoritative and cutting-edge, Mammary Stem Cells: Methods and Protocols aims to help members of the scientific community explore the behavior of stem cells and how to work with them in order to guide the design of new and complimentary strategies to be applied in the clinic with the ultimate end goal of fighting breast cancer.