Cover photograph (Copyright © 2008, American Society for Microbiology. All Rights Reserved.): Nkx6.1 increases β-cell replication. This image is a computer-enhanced rendering of an islet section after treatment with an adenovirus overexpressing the transcription factor Nkx6.1, demonstrating the ability of this protein to increase β-cell replication. Islets are composed primarily of cells expressing either insulin (green) or glucagon (blue). Nuclei undergoing replication are detected by incorporation of bromodeoxyuridine (red). Confocal micrographs of rodent islets were used to generate this image. (See related article on p. 3465.)