Mice maintained on the high fat/high cholesterol diet for 4 weeks received 2 μCi of [14C]cholesterol, 0.2 mg of cholesterol, and 0.5 μCi of [3H]sitostanol in 100 μl of olive oil by stomach gavage. Fecal matter was collected after 24 and 48 h, homogenized in water, and then extracted with chloroform/methanol (2:1, v/v). Scintillation counting was used to determine the amount of radioactive sterols present in the organic phase. Recovery of nonabsorbed cholesterol in feces was corrected based on the amount of [3H]sitostanol in each sample. Absorption of cholesterol is presented as a percentage of the administered dose and is representative of two experiments. Shown is the means ± S.E. for n = 9 wild type (WT), n = 7 PTL−/−, n = 10 CEL−/−, and n = 9 PTL−/−,CEL−/− mice. *, p < 0.05; **, p < 0.01 (differences from wild type mice).