Human embryonic stem cells (hESCs) can be changed into virtually any cell type in the adult body. Because of this unique capability, these cells have the potential to cure many human diseases. Several hurdles exist and need to be overcome before results from the exciting field of stem cell research can be used in the clinic. One of these hurdles is that the change of stem cells into differentiated cells often produces a complicated mixture, consisting of cells from several different tissue types. A current challenge at the forefront of hESC research is to obtain pure differentiated cells that can be used for medical applications. For example, nerve cells may be required for repairing spinal cord damage. Our research focuses on finding ways to identify neuronal cells and their precursors from amongst the cacophony of stem cell differentiation products. In the past year, we have discovered several markers of neuronal differentiation. These markers may be important for understanding basic biological functions of stem cells.