 We know that turning genes on and off is crucial to the process differentiation, so we can add some factor into the culture dish and observe stem cells to differentiate into specific types of cells. But some sort of signal is needed to actually trigger the stem cells to differentiate. We are still searching for that signal. If we can ultimately learn how to direct stem cells to differentiate into one type of tissue or another, then we can use them to treat patients. In this proposal, we will first examine this step. 