Fig. 4. Nuclear GFP containing the membrane targeting motifs of N-Ras induces intranuclear vesicular structures. HeLa cells transiently transfected with NLS-MT-GFP-N-Ras (A-C) or NLS-MT-GFP (D) chimeras were fixed 24 hours after transfection and examined by fluorescence confocal laser scanning microscopy. In A an overlay of the GFP fluorescence and differential interference contrast picture is shown. Note the presence of brightly fluorescing vesicular structures inside nuclei of cells expressing high levels of the chimeric GFP in C. Bar, 10 µm (A); 20 µm (B-D).