Unlike some parents, adult stem cells don't seem to mind when their daughters get a tattoo. In fact, they're willing to pass them along. Using the molecular equivalent of a tattoo on DNA that adult stem cells (ASC) pass to their "daughter" cells in combination with gene expression profiles, University of Utah researchers have identified two early steps in adult stem cell differentiation—the process that determines whether cells will form muscle, neurons, skin, etc., in people and animals.