My lab has worked on breast cancer research for more than 12 years in collaboration with the lab of with Professors Visvader and Lindeman. In particular we have worked to understand the development of mammary cells and to identify the likely cells of origin for different types of breast cancer. In a recent study, we conducted scRNA-seq profiling of 20,000 mammary epithelial cells from mice at various life stages from pre-puberty to puberty, adulthood, pregnancy, estrus and diestrus. I will present some of the results form this study and will discuss some of the computational and statistical approaches used to interpret the data.