Three papers published this past Sunday touch upon different aspects of the aging problem. The first one appeared in Nature and is authored by Rui Yi and colleagues, who found that microRNA-203 promotes the differentiation of skin stem cells by repressing “stemness”. In stratified epithelia, stem cells located basally are crucial for self renewal. As these cells leave the basal zone, they differentiate and cease to behave like stem cells. What the authors found is that microRNA-203 is crucial for this differentiation process, leading the stem cells to exit the cell cycle. Mechanistically, this effect depends on repression of p63 expression, a molecule that had previously been shown to regulate stem-cell maintenance in epithelia.