Cover photograph (Copyright © 2006, American Society for Microbiology. All Rights Reserved.): Induction of chromatin assembly factor CAF-1 expression in response to DNA strand breaks in quiescent human cells. Shown is a confocal immunofluorescence micrograph of a nucleus from a damaged quiescent human cell. DNA strand breaks were generated in cultured human cells by the radiomimetic drug bleocin. This treatment induced the expression of CAF-1 and led to its recruitment to chromatin in the damaged cell nuclei. Red, chromatin-associated CAF-1; green, sites of DNA double strand breaks, detected by antibodies specific for phosphorylated histone H2AX. (See related article on p. 1839.)