Functional heterologous NLS and NES sequences. (A) Schematic of MxB nuclear localization mutants. The location of heterologous NLS and NES sequences are denoted in blue and red, respectively; the common C-terminal HA tag is in green. Western blotting (B), antiviral activity (C), and immunofluorescent microscopy (D) of WT MxB and mutant proteins. Results in panel C represent the geometric mean of at least 8 independent experiments, with error bars denoting 95% confidence intervals. The differences in HIV-1 restriction by MxB Δ1-25 or MxB + NES with WT MxB was highly significant (P <0.0001). The horizontal bars in panel D represent the distance of 10 μm.