Research Interests The mammalian skin epithelium (epidermis) is an ideal model system to study fundamental questions in stem cell and cancer biology. It is accessible; it can be cultured, genetically manipulated and transplanted; and its resident stem cells possess unparalleled regenerative capacity. Our skin, unlike many other organs, undergoes continuous growth and turnover. And unlike other “simple” epithelia, the epidermis is stratified, consisting of many cell layers with specialized functions. In development and homeostasis, progenitors in the skin must balance self-renewal and differentiation programs. We have found that asymmetric cell divisions are a critical mechanism by which skin progenitors maintain this equilibrium. We are interested in studying how this asymmetry is controlled at a molecular level, and how division orientation impacts cell fate choices in normal and neoplastic growth. To facilitate these and other studies in diverse epithelia, we have developed a powerful functional tool, in utero lentiviral RNAi (see figure, below), which allows us to rapidly perform functional studies on any gene in the intact mouse in weeks instead of years. Our broad goal will be to use this technique, in combinations of candidate and screening approaches, to dissect pathways that influence epithelial differentiation.