(A) Representative images of COS7 cells expressing GFP-COP1 (green) co-transfected with empty vector or the indicated TRIB1-FLAG construct (red). Cells were stained with anti-FLAG (Sigma) and anti-mouse Alexa Fluor 568. Nuclei were counterstained with DAPI (blue). Scale bar, 10 µm. See also Appendix Fig S1B for western blots showing the expression levels of the constructs used. 