The present invention relates to a method of isolating stem cells from a mixed population of different cell types. This method involves selecting a promoter which functions only in said stem cells and not in the other cell types. The promoter can have a nucleotide sequence selected from the group consisting of SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, and SEQ ID NO: 8. A nucleic acid molecule encoding a marker protein under control of said promoter is introduced into all cell types of said mixed population and only the stem cells, but not the other cell types, within said mixed population are allowed to express said marker protein. The cells of said mixed population of cell types that are expressing the marker protein, which are restricted to the stem cells are identified and separated from the mixed population, where the separated cells are restricted to the stem cells. The promoter, nucleic acid constructs comprising it, and the resulting stem cells are also disclosed. The nucleic constructs can be incorporated in transgenic animals in order to monitor stem cell movement. A disorder mediated by stem cell proliferation can be carried out by administering both (1) a nucleic acid construct comprising the promoter of the present application and an enzyme capable of converting a prodrug to a cytotoxic drug and (2) the prodrug.