ABCA1 response to cholesterol loading. CHO cells stably expressing ABCA1 were incubated for up to 8 h in either low cholesterol (control) medium (0.5% FBS) or cholesterol-enriched medium (0.5% (v/v) FBS supplemented with cholesterol/CD (20 μg cholesterol/ml) (Chol-loaded). A, cholesterol content of cells before (T = 0 h) and after incubation for 8 h with or without cholesterol. The data are means ± S.D. of a single experiment (n = 3). B, Western blot showing cellular ABCA1 protein after 8 h with or without cholesterol. C, ABCA1 mRNA levels measured after 8 h of incubation with or without cholesterol. The data are means ± S.D. of a single experiment (n = 6). D, cells were incubated for the indicated times with medium containing 0.5% FBS and cycloheximide (10 μg/ml) in the presence (white circles) or absence (black circles) of cholesterol/CD (20 μg cholesterol/ml). The data are means ± S.D. (n = 6) of a single experiment representative of four independent experiments. A representative Western blot from a single experiment is shown below. *, p < 0.05 relative to control cells.