Why is NPM localized in nucleoplasm in drug treatment control cells?

[chen219 from purdue.edu]

I treated A549 and Hela cells with ActD, MPA, DOX and Anisomycin, using DMSO,  
EtOH, H2O and MeOH as vehicle control, respectively. NPM is localized in 
nucleoplasm in all the cells including vehicle control cells. I don't know how 
to explain this phenomenon. Have anyone had any experience in this kind of 
experiments? Does anyone have any thoughts?

Li