Chow diet-fed MTP and ABCA1 gene ablated mice absorb less lipids. 12-Week-old WT, I-Mttp−/−, I-Abca1−/−, and I-DKO male mice (n = 3) were fasted overnight and injected intraperitoneally with poloxamer 407 (30 mg/mouse). After 1 h, mice were gavaged with 0.5 μCi of [14C]triolein or [3H]cholesterol and 0.2 mg of cholesterol in 15 μl of olive oil. Plasma was collected 2 h after the gavage of radiolabeled lipids and used to measure triglycerides (A) and cholesterol (B) concentrations. Total plasma was also used to measure radioactivity to determine the absorption of [14C]triolein (C) and [3H]cholesterol (D). Plasma was precipitated as described under “Materials and Methods” to determine radioactivity cholesterol counts in non-HDL (E) and HDL (F) lipoproteins. Values are mean ± S.D. *, p < 0.05; **, p < 0.01; ***, p < 0.001 compared with WT.