Volume 122 of Methods in Cell Biology describes modern tools and techniques used to study nuclear pore complexes and nucleocytoplasmic transport in diverse eukaryotic model systems (including mammalian cells, Xenopus, C. elegans, yeast). The volume enables investigators to analyze nuclear pore complex structure, assembly, and dynamics; to evaluate protein and RNA trafficking through the nuclear envelope; and to design in vivo or in vitro assays appropriate to their research needs. Beyond the study of nuclear pores and transport as such, these protocols will also be helpful to scientists characterizing gene regulation, signal transduction, cell cycle, viral infections, or aging. The NPC being one of the largest multiprotein complexes in the cell, some protocols will also be of interest for people currently characterizing other macromolecular assemblies. This book is thus designed for laboratory use by graduate students, technicians, and researchers in many molecular and cellular disciplines.