Internalization of CPP by RAW 264.7 cells.

<p><b>A,</b> RAW 264.7 macrophage were seeded on coverslips and incubated with 100 µg/mL AlexaFluor488-labeled fetuin-A-containing synthetic CPP (green) in DMEM culture medium supplemented with 10% FBS for 30 minutes at 37°C, with (right-hand side panel) or without (left-hand side panel), quenching of cell-surface fluorescence using anti-AlexaFluor488 IgG (80 µg/mL), or PBS as control, for 1 h at 4°C. Cells were then washed, fixed, mounted in ProLong Gold antifade reagent and visualized by confocal microscopy. <b>B</b>, TEM of murine RAW 264.7 macrophage treated with 100 µg/mL CPP-containing culture medium supplemented with 10% FBS for 1 h at 37°C. The dashed box outlines a vacuole containing CPP (bar = 1 µm). <b>C</b>, magnified image of box shown in A (bar = 200 nm). Black arrowheads indicate position of vacuolated CPP near the cell surface.