Fig. 4

NES2 and NLS2 are functional export and import signals in heterologous reporter constructs. U2OS cells were transiently transfected with GFP constructs fused to the wild-type or mutated versions of NES2 or NLS2, fixed and prepared for fluorescence microscopy (a, c). Representative images of at least three independent experiments are shown. Scale bars: 10 μm. b, d Mean fluorescence intensities in nuclei and cytoplasm of GFP-NES2wt, GFP-NES2mut (b), GFP-NLS2wt or GFP-NLS2mut (d) transfected cells were measured in original unprocessed digital images prior to contrast/brightness adjustment, and nucleus to cytoplasm signal ratios were calculated. Data were obtained from three independent experiments and analyses were done using Student’s t-test. GFP-NES2mut, P = 7.9E-30; GFP-NLS2mut, P = 9.1E-18; n = 43; 13–15 cells each from three independent experiments