Figure 2.

Nuclear import of cyclin B1–Cdc2 does not occur by the NLS-dependent pathway. Nuclear import reactions were performed with interphase cytosol and cyclin B1E–Cdc2K⁻ (A–C), wild-type cyclin B1–Cdc2 (D–F), or FITC-labeled NLS-BSA (G–I), in the absence of inhibitors (A, D, and G) or in the presence of 100 μM NLS peptide (B, E, and H) or 2 μM IBB domain (C, F, and I). Cells were analyzed by direct immunofluorescence (G–I) or were fixed and analyzed by secondary immunofluorescence with antibodies against the Myc epitope tag (A–F).