Figure 6. Serum deprivation treatment increases intracellular cholesterol in ARPE-19 cells. A: Confocal images of Transwells with confluent ARPE-19 cells stained for cholesterol with filipin (blue). The left panel shows cells in serum containing medium (serum); the right panel shows cells in serum-free medium (serum free) for 7 days before staining. Maximum intensity projections from confocal z-series at 40X magnification are shown. Identical settings were used for both images. Scale bars=50 µm. B: Quantitation of free and total cholesterol. Serum-free treatment increases total cholesterol and free cholesterol levels in confluent ARPE-19 cells relative to cells grown in serum (n=4, mean ± standard error of the mean [SEM]).