Effect of ATRA on LPS-induced TF promoter activity in THP-1 cells. pTF(−2106)LUC (6 μg) was transfected into THP-1 cells using DEAE-dextran. After 46 hours, cells were divided into four equal portions and were treated with LPS (10 μg/mL) for 5 hours with or without a 30-minute pretreatment of ATRA (1 × 10⁻⁵mol/L). The control sample was incubated without LPS or ATRA. Luciferase activity (light units) expressed by pTF(−2106)LUC was used to determine fold inductions (mean ± SE) in three independent experiments.