Fig. 2. The nuclear localization of mSTI1-EGFP is enhanced by inhibition of nuclear export and inhibition of cdc2 kinase but not by inhibition of CKII. (A) Untransfected NIH3T3 fibroblasts (left), NIH3T3 fibroblasts stably transfected with pBEGFP (middle) or with pB-mSTI1-EGFP (right) were exposed to leptomycin B (18.5 nM), olomoucine (0.1 mM) or DRB (0.3 mM) for 3 hours, 8 hours and 8 hours, respectively. Untransfected cells were immunostained to detect endogenous mSTI1 with SF1 polyclonal rabbit anti-mSTI1 and Cy3-conjugated donkey anti-rabbit antibodies, and transfected cells were fixed in 3.7% paraformaldehyde before mounting and visualization by confocal laser fluorescence microscopy. Scale bars, 10 µm. (B) Cells as above were exposed to leptomycin B, olomoucine and DRB, and cells demonstrating cytoplasmic fluorescence or nuclear and cytoplasmic fluorescence were quantified. The error bars represent standard deviations.