Karyopherin, a cytosolic and heterodimeric protein complex consisting of alpha and beta subunits, is responsible for targeting proteins with nuclear localization signals to the nuclear pore complex by an energy requiring, Ran-dependent mechanism. The alpha subunit and imported substrate enter the nucleus and accumulate in the nucleoplasm, while the beta subunit accumulates at the NPC. KPNA2 is the alpha subunit 2 of karyopherin, which forms a complex with importin subunit beta-1 and functions as a cargo carrier that transports various complexes from cytoplasm into nucleus. It is ubiquitously expressed and contains an IBB/importin beta domain, ten Armadillo repeats that bind “cargo” and three intervening nuclear localization sequences (NLSs). It has recently been reported to play an important role in tumorigenesis and tumor progression.