In higher eukaryotic cells, the secretory and endocytic membrane systems are comprised of a series of biochemically and morphologically distinct compartments. Dynamic associations with cytoskeletal networks have been shown to mediate both membrane transport between these compartments as well as maintenance of their characteriztic spatial distributions within the cell. More specifically, in endocytosis, association with microtubules and the action of microtubule-associated motor proteins are necessary for the proper positioning of late endosomes, lysosomes, and the pericentriolar recycling compartment (1-3). In addition, efficient transport of cargo between early and late endosomes, and transcytosis in polarized epithelial cells, also depend on microtubule-associated motors (4,5).