Cover legend: Transverse section through the neonatal spinal cord of a double-transgenic mouse engineered so that ubiquitous expression of a β-galactosidase/neo fusion protein is replaced by that of GFP specifically in cells that express glial fibrillary acidic protein. Section is labeled with antibodies against GFP (green), the neuronal marker NeuN (red), and β-galactosidase (blue). For more information, see the article by Garrett and Weiner in this issue (pages 11723–11731).