Effect of oxysterols on the endocytic pathway. Lens epithelial cells were incubated with RITC-dextran for 30 min, at 37°C, following incubation with 20 μg/ml cholesterol (B), 7-keto (C) or 25-OH (D) for 2 hours. Cells incubated with 0.2% ethanol were used as controls (A). The cells were incubated for an additional 30 min in the absence of the dye, and subsequently fixed with 4% PFA and imaged by fluorescence confocal microscopy. For negative controls, cells were incubated at 4°C to inhibit endocytosis (E).