Dr. Morris' interests and research are focused on the keratinocyte stem cells of the cutaneous epithelium and their role as target cells for carcinogens and tumor promoters. One major effort in her lab is the identification and isolation of epidermal stem cells and target cells by means of a novel application of selection procedures to determine their molecular phenotype. This approach has recently enabled the enrichment for living keratinocyte stem cells from the hair follicle bulge with the cell surface marker, CD34. A second project in the Morris lab is a transgenic approach to the fate mapping of candidate stem cells in the hair follicles in the normal cycle of hair growth and differentiation and during carcinogenesis. A third research focus in the lab is to determine intrinsic and extrinsic factors regulating the number of keratinocyte stem cells with an eye to the identification of novel stem cell control genes. This approach has recently led to the identification of stem cell regulatory loci implicated in skin carcinogenesis. The ability to identify and to isolate subpopulations of keratinocyte progenitors will enable the determination of molecular differences among them, and will provide a basis for the identification of new genes having a critical role in epidermal growth, differentiation, stem cell self-renewal, and carcinogenesis. Furthermore, prospective identification of stem cells and their regulatory genes in the cutaneous epithelium should suggest new diagnostic markers as well as new therapeutic targets and strategies for cancer prevention.