Fig. 3. Kaiso deletion mutants are insensitive to the CRM-I-dependent nuclear export inhibitor leptomycin B. To verify that there were no additional NLS in Kaiso whose activity was masked by a stronger, out-competing NES, we transfected HeLa cells with the indicated constructs, and then treated HeLa cells with either vehicle alone (A) or 50 nM leptomycin B (B) for 16 hours before paraformaldehyde fixation and imaging. None of the Kaiso deletion mutants were sensitive to leptomycin B, indicating that none of these constructs encoded a dominant CRM-I-dependent NES that masked a weaker NLS. The images shown are representative of at least two independent trials. Bars, 20 µm.