For this project, investigators used both mouse- and human-derived stem cells, obtained from embryos and adult tissues. At the end of the project, approximately 1000 stem cell samples and 300 purified stem cell populations were isolated; some of the cells types included myoblasts, as well as embryonic, hematopoietic and neural stem cells. The investigators used global gene expression platforms, including Affymetrix GeneChips and SAGE (serial analysis of gene expression) to identify the genetic factors regulating stem cell maintenance and development. In addition, various protein analyses were performed to generate global profiles of protein activity and function. A comprehensive overview of the genetic factors that specify stem cell identity and regulate their ability to differentiate will allow the full exploitation of the potential of stem cells in a clinical setting.