IN interaction as observed by the BiFC assay system. EGY48 yeast cells were transformed using the lithium acetate method with plasmids encoding the following combinations: GN-IN and GC-IN, GN-IN and GC-LEDGF, GN-IN and GC-linker (control), GN-IN and GC-Impα (importin α), GN-180-IN and GC-Impα, GN-NLS-IN and GC-Impα, GN-152-IN and GC-Impα, GN-IN and GC-Impβ (importin β), GN-Rev (HIV-1) and GC-Impα. Restoration of GFP fluorescence was observed by confocal microscopy. All other experimental conditions were as described in Methods. Bar 10 μm.