Nkx2-2 homeoprotein is essential for the development of the central nervous system and pancreas. Although the nuclear localization signals of Nlcx2-2 have been identified, the responsible transport receptor is still unknown. Here, we demonstrate that imp alpha 1 not only interacts with Nkx2-2 but also transports it into the nucleus in vitro by acting together with imp beta(1) However, the nuclear import of Nkx2-2 in cells was not inhibited in response to knockdown expression of endogenous imp beta 1 or over expression of Bimax2. Furthermore, imp beta 1 and imp 13, but not imp 4, directly interact with Nkx2-2 and are capable of transporting Nkx2-2 in an in vitro import assay. By GST pull-down assay, we demonstrate that mutation of NLS1 or NLS2 has no effect on interaction with imp alpha 1 or imp 13, but significantly reduced binding to imp beta 1. Thus, the nuclear import of Nkx2-2 is mediated not only by the classical import pathway but also directly by imp beta 1 or imp 13. (C) 2016 Elsevier Inc. All rights reserved.