Expression of Ub-EEA1 inhibits transferrin uptake. COS7 cells transfected with EEA1- or Ub-EEA1-expressing plasmids were treated with Texas red-labeled transferrin on ice. After removal of unbound transferrin, cells were incubated in a transferrin-free medium at 37°C for the indicated time points. Cells were fixed and stained with anti-EEA1 antibody (green) and DAPI (blue). Note that the highlighted Ub-EEA1-expressing cells fail to take up transferrin compared to the surrounding untransfected cells.