(a) The hepatic cholesterol levels in the ABCG5/ABCG8 transgenic and wild-type mice. Individually housed male and female 12-week-old mice of the indicated genotypes were fed a powdered chow diet (0.02% cholesterol) or the same diet containing 2% cholesterol for 21 days. The mice were sacrificed without fasting in the mid–light cycle. The livers were obtained and rapidly frozen in liquid nitrogen. Lipids were extracted and the hepatic cholesterol content was measured as described in Methods. The values shown represent the means of individual measurements in each experimental group (n = 5). (b) Quantitative real-time PCR from liver RNA of ABCG5/ABCG8 transgenic and wild-type mice. Total RNA from the liver of mice in each group (n = 5) was isolated and pooled for real-time PCR using oligonucleotides as described (18, 39). Cyclophilin was used as an internal control for these studies, and the values represent the amount relative to the amount in the chow-fed wild-type males, which was arbitrarily standardized to 1. This experiment was repeated in the 6-1 transgenic mouse line, and the results were similar.