NTF97, also known as KPNB1, is a member of the importin beta family. This protein is involved in nuclear protein import, either by associating itself with an adapter protein (for example, importin-alpha subunit which binds to nuclear localization signals (NLS) in cargo substrates), or by acting autonomously as a nuclear transport receptor (serves as NLS receptor, docking of the importin/substrate complex to the nuclear pore complex).