(A) Representative images of COS7 cells transiently transfected with GFP-COP1 WT or GFP-COP1 NESmut (V238A/L242A) (green) and empty vector or 3xFLAG-CRM1 (grayscale). Cells were stained with anti-FLAG (Cell Signaling) and anti-rabbit Alexa Fluor 680. Nuclei were counterstained with DAPI (blue). Scale bar, 10 µm. 