Human embryonic stem cells have the potential to proliferate indefinitely in culture while at the same time have the ability to give rise to any cell type present in the human body. As such they represent an important new tool for understanding the underlying causes of disease, for developing new, safer drugs to treat disease and for cell-based therapy for treating a wide range of human diseases and disorders. But the molecular mechanisms regulating human embryonic stem cell growth are still poorly understood. In our studies we have begun to understand how a key growth factor signaling pathway acts to regulate the growth and survival of embryonic stem cells. Importantly we have shown that one of the key factors controlling the stem cell state acts in part to control the expression of growth factor receptors on the stem cell membrane. In addition we have begun to understand how that growth factor signaling pathway acts through distinct pathways to control the so-called stem cell state. So far our studies have elucidated how this growth factor signaling pathway is controlled and how it itself controls events within the stem cell. Our studies suggest that signaling from growth factor receptors acts through factors in the cell nucleus to feedback on regulatory machinery to conrtol the stem cell state. Several of these results have been published. Improving our understanding of how the stem cell state is regulated will improve our ability to grow stem cells for all of the possible uses of the cells described above. That in turn will accelerate the development of our understanding of human disease and the development of new treatments for human diseases, disorders and injuries.