Amino acids 386 to 393 of BGLF4 are important for its nuclear localization but do not compose a canonical NLS. (A) HeLa cells were transfected with plasmids expressing wild-type BGLF4 or d(386-393), R386A, K393A, ([R386A/K393A], 2A), ([K389, 390A/R391A], 3A), or ([K386, 391A/K389, 390, 393A], 5A) mutants. At 24 h posttransfection, cells were fixed and stained for BGLF4 and DNA with rabbit BGLF4 antiserum and Hoechst 33258. (B) Transfected HeLa cells were also subjected to subcellular fractionation to separate nuclear (N) and cytosolic (C) fractions. All BGLF4 mutants were detected with BGLF4 monoclonal antibody 2616. PARP and α-tubulin were detected as nuclear and cytoplasmic markers, respectively.