ABSTRACT
In order to investigate the mechanism of stat3 nuclear import. positioned a characterized NLS of the SV40 large T antigen into Stat3-GFP, Dstat3-GFP respectively between the C-terminus of Stat3 and the N-terminus of GFP to create Stat3-NLS-GFP and Dstat3-NLS-GFP. With NLS-GFP as the positive control, Expression of the Stat3-NLS-GFP without IL-6 stimulation and Stat3-GFP with IL-6 stimulation resulted in a predominantly nuclear localization in 293T cell. Expression of Stat3-GFP and Dstat3-NLS-GFP without IL-6 stimulation resulted in predominantly cytoplasm localization in 293T cell. The results suggest that latent Stat3 is not anchored in the cytoplasm, and that nuclear localization in response to IL-6 is facilitated by gain of an NLS function.