Sanguinarine induces long-term disruptions in cyclin D1 trafficking. Cultures were fixed and immunolabeled with an antibody to cyclin D1 (green) and counterstained with Hoechst to visualize DNA (blue). DIC, differential interference microscopy. (a-c) Control cells, showing that cyclin D1 labeling is restricted to nuclei, which vary in labeling intensity. (d-f) Culture treated with 5 μM sanguinarine for 24 hours. Note the appearance of bright cytoplasmic speckles of cyclin D1 immunofluorescence (arrows), while the overall nuclear labeling intensity appears to be diminished. (g-i) Culture allowed to recover in drug-free media for 48 hours after a 24 hour pulse of 5 μM sanguinarine. Cytoplasmic deposits of cyclin D1 (arrows) are still present in many cells.