Cover photograph (Copyright © 2003, American Society for Microbiology. All Rights Reserved.): Anticortactin antibodies stain honeycomb clathrin-coated pits found along the plasma membrane of eukaryotic cells. Gold-tagged secondary antibodies (yellow dots) were applied to cultured BHK cells that were first unroofed and exposed to primary cortactin antibodies before preparation for electron microscopy by the deep-etch technique. Morphological and functional observations suggest that cortactin participates in plasma membrane deformation during receptor-mediated endocytosis. Cortactin is known to interact with the large GTPase dynamin and remodel the actin cytoskeleton in response to c-src phosphorylation. These properties make cortactin a likely candidate to regulate the clathrin-based endocytic process. Magnification, x35,000. (See related article on p. 2162.)