The image shows a postnatal mouse cerebellum stained for Pax2 (green) and NeuN (red), highlighting immature inhibitory interneurons and excitatory granule cells, respectively. Shh signaling promotes the expansion of Pax2 progenitors that contribute selectively to the stellate cell pool, one of two molecular layer interneuron subtypes. For more information, see the article by Li, Chen et al. (pages 5130–5143). Cover image: Wen Li.