Cover photograph (Copyright © 2002, American Society for Microbiology. All Rights Reserved.): Hydrophobic pocket of human cyclin D1 (derived from a spatially constrained model based on cyclin A3 coordinates) bound to an RXL motif derived from p107. Interaction of the RXL motif in p107 with cyclin D1 is important for cyclin D1/Cdk4-dependent inactivation of p107 via direct phosphorylation. (See related article on p. 2242.)