APP-GFP traverses the endocytic pathway. (a) COS-7 cells transfected with Wt APP-GFP were exposed for 3 h to the protein synthesis inhibitor CHX and incubated in the last 15 min with Texas Red-conjugated transferring. Co-localization (yellow/orange fluorescence vesicles) between transferrin (Texas red endocytic vesicles) and APP-GFP green cytoplasmic vesicles can be observed (Overlay panel). Immunocytochemistry analysis with (b) an early (Rab 5) and (c) late (Rab 7) endosomal markers were also performed and co-localization observed. ROI, region of interest, denotes APP-GFP co-localizing endocytic vesicles. Bar, 10 μm. Fluorescence intensity profiles are also presented, representing the voxels through the white arrowed lines indicated in the ROI overlay images; asterisks denote co-localizing vesicles. A microphotograph of the eGFP protein is presented as a negative control, GFP alone is distributed through the nucleus and cytoplasm, but is not targeted to cytoplasmic vesicles.