Colocalization of TAT-SA with endocytic markers in living cells. (A) HeLa cells were transduced first with TAT-SA-A488 (green) and then with TRITC-labeled transferrin (TRITC-Tf, red), a marker clathrin-mediated endocytosis, prior to analysis with confocal microscope at 15 min post transduction. (B) Cells transduced with TAT-SA-A488 and fluid-phase endosomal marker TRITC-labeled dextran (10 kD, red) were monitored at 15 min and (C) at 4 h post transduction. The white rectangles show the close-ups of representative structures. Scale bars, 10 μm.