In the cytoplasm, cargo containing a cNLS is bound by the heterodimeric import receptor, importin α/importin (32). Importin α recognizes the cNLS, and importin β mediates interactions with the nuclear pore during translocation. Once inside the nucleus, RanGTP binding causes a conformational change in importin β, which releases the IBB region of importin α. This autoinhibitory domain, together with Nup2 and Cse1, facilitates cNLS dissociation and delivery of the cNLS cargo in the nucleus (35, 36). Finally, importin α is recycled back to the cytoplasm by the export receptor, Cse1, in complex with RanGTP (40, 41).