A pool of endocytic APP-GFP is targeted to the TGN. Wt APP-GFP at COS-7 cell surface was labelled by incubating cells with the 22C11 anti-APP ectodomain antibody ("22C11 Uptake", Texas red staining) at 4°C. At 0 min, 22C11 staining is maintained at the cell surface (microphotographs taken at the plasma membrane focal plane). Following 15 min at 37°C, part of the 22C11 population can be observed at vesicular structures around the Golgi (arrowhead; microphotographs taken at the Golgi focal plane). Endocytic 22C11/APP-GFP targeting to the TGN was confirmed by co-localization with a pECFP-Golgi construct ("CFP-Golgi", blue fluorescence), a construct targeted to the trans and medial region of the Golgi. Of note, since the CFP-Golgi fusion protein has a weak blue fluorescence, it is virtually non-visible at the plasma membrane focal plane. ROI - region of interest, 2.0-fold magnified. Several white vesicles, denoting 22C11/APP-GFP/CFP-Golgi co-localization, can be observed at the TGN (arrows in ROIs), A tubular morphology can be depicted for some of these vesicles in the ROIs. Bar, 10 μm.