The nuclear pore complex (NPC) is a structure that spans the nuclear envelope and provides a conduit between the nucleus and cytoplasm for the nucleocytoplasmic transport of macromolecules. The main components of the NPC are nucleoporins. About 30 different human Nups have been identified and appear to serve non-redundant functions. Nup107 is essential for the assembly of peripheral proteins in the NPC. It has also been observed to localize to kinetochores in a subcomplex with NUP160 and is essential for proper mitosis.