FIGURE 2.

ABCG1 response to cholesterol loading. CHO cells stably expressing ABCG1-678 were incubated for up to 8 h in either low cholesterol (control) medium (0.5% FBS; control) or cholesterol-enriched medium (0.5% 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 three independent experiments. B, Western blot showing cellular ABCG1 protein after 8 h with or without cholesterol. C, time course of ABCG1 protein expression during incubation with (white circles) or without (black circles) cholesterol. The data are means ± S.D. of six independent experiments. Representative Western blots from a single experiment are shown. D, ABCG1 mRNA levels measured after 8 h of incubation with or without cholesterol. The data are means ± half-range of two separate experiments. E, ABCG1 protein after 8 h of incubation without (Control) or with (Comp/Mev) compactin (5 μm) plus mevalonate (50 μm). F, ABCG1-dependent [³H]cholesterol efflux after preloading cells with or without unlabeled cholesterol. For E and F, the data are means ± S.D. of triplicate cultures in a single experiment. *, p < 0.05 relative to control cells.