AAT increases intracellular cholesterol levels. Cells were incubated with AAT for the indicated time periods. The intracellular cholesterol was stained with filipin, as described in the Materials and Methods. Filipin fluorescence appears shortly after stimulation with AAT and enhances in a time-dependent manner. Images were acquired with constant exposure time and under the same magnification for the whole series. Representative images of three independent experiments are shown. Scale bar = 20 µm.