Fig. 4

Morphological changes upon combined Dynasore-E2 treatment of MCF-7 cells. Semithin frozen sections of control MCF-7 cells labeled with antibodies directed against ER-α (green) and caveolin-1 (red). a–c ER-α receptor labeling occurred inside the cytoplasm and the plasma membrane in MCF-7 cells. Nuclear occurrence of the receptor could also be observed, however, to a lesser extent. The merged image of ER-α and caveolin-1 double labeling shows overlapping areas at the plasma membrane (arrowheads), while intracytoplasmic co-labeling could also be detected. Bars indicate 10 µm, nuclei were stained with DAPI. d Ultrathin cryosection shows morphologically distorted, elongated caveolae (arrowheads) indicating the effect of Dynasore treatment. Larger gold particles labeling ER-α could be observed in the close vicinity of caveolin-1 positive structures right beneath the plasma membrane (P). Note that the deeper cytoplasmic areas lack both small (ERα) and larger (caveolin-1) gold particles indicating the disturbed internalization of caveolin-1 positive vesicles. Bar indicates 200 nm