The invention pertains to a novel enhancer element that selectively controls expression in ASCL2-positive cells, such as intestinal and colon stem cells and stem cells in colorectal cancer.The invention further concerns a nucleic acid fragment and construct comprising this element as well as the use of the element in the treatment of a disease, especially a proliferative disease. The invention further relates to a method for detecting an ASCL2-positive cell and a cell comprising the enhancer element.