Quantitative RT-PCR analysis of TNF-α regulated genes in U937 cells after sequential treatment with PGSE and TNF-α. U937 cells (1 × 106) were pretreated with or without 3 mg/ml PGSE for 24 hours and followed by 20 units/ml of TNF-α for 2 hours. DNase-treated RNA samples were reverse transcribed and the levels of mRNA induction of (A) CXCL-10, (B) IL-8 and (C) TNFAIP3 as well as the reference gene 18S rRNA were determined by gene-specific TaqMan assays as described in Methods. The levels of induction were relative to the untreated cells. Values represent the average ± SD of three independent experiments and statistically analyzed by two tailed, paired t-test. *: p < 0.05. PGSE, 70% ethanol-water extracts of ginseng; CXCL-10, interferon gamma-inducible protein-10; IL-8, interleukin-8; TNFAIP3, TNF-α-induced protein 3.