ABCA1 is involved in the apoA1-mediated increase of TTP expression in LPS-treated macrophages. A, THP-1 macrophages were transfected with control (WT) or ABCA1 siRNA for 48 h, and protein samples were immunoblotted with ABCA1 antibody. Ctrl, control. B, THP-1 macrophages transfected with control (WT) or ABCA1 siRNA were treated with apoA-I for 20 min. p-STAT3 expression was analyzed by Western blot. *, p < 0.05 versus control group. C, THP-1 macrophages transfected with control (WT) or ABCA1 siRNA were treated with LPS alone or with pretreatment of apoA-I for 4 h. TTP expression was analyzed by Western blot. *, p < 0.05 versus control group. D, THP-1 macrophage-derived foam cells transfected with control (WT) or ABCA1 siRNA (ABCA1−/−) were treated by LPS alone or with apoA-I for 3 h followed by addition of act D (5 μg/ml) to stop transcription. After the indicated time points, TNF-α mRNA was quantified using RT-PCR. Values were normalized against β-actin. Remnant TNF-α mRNA in percentage of the amount at the time point 0 of act D treatment was depicted. *, p < 0.05 compared with other groups. All of the data represent the mean ± S.E. from three separate experiments with triplicate samples.