Limited understanding of the cell biology of the breast and breast cancer hampers our ability to develop new therapeutic approaches. Mouse models of mammary gland development and tumourigenesis are key to developing new insights into the biology of both the normal and diseased tissues. Recent advances have enabled the isolation, molecular characterisation and functional analysis of mouse mammary epithelial cell subpopulations from the normal gland, including subpopulations enriched for stem cell behaviour. Application of these techniques both to the normal mammary gland and to tumour models will promote a better understanding of the nature of the different epithelial cell types in the mammary gland, the origins of mammary tumours and the role of tumour stem cells.
