Glucocorticoid receptor signaling cells

Most current assays use immunofluorescence or GFP fluorescence to evaluate the nucleocytoplasmic distribution of endogenous nuclear proteins (Corbett et al., 1995 Lim et al, 1995 Schlenstedt et al, 1995) or NLS-containing reporter proteins (Nehrbass et al, 1993 Schlaich and Hurt, 1995) in the steady state. These methods are usually sensitive only to defects that severely impair the transport apparatus (see example below). Even the use of inducible promoters to express reporter proteins after shifting cells to nonpermissive conditions (Corbett et al, 1995 Schlenstedt et al, 1995) requires at least 30-60 min to produce an adequate signal and is, therefore, often too slow. A clever assay was recently described to measure defects in nuclear export signal-mediated protein export in yeast (Lee et al, 1996). An attractive in vivo approach now in use in tissue culture cells is the application of hormone-stimulated GFP-glucocorticoid receptor import to study import kinetics (Htun et al, 1996 Carey et al, 1996). 

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