Down-regulation of IL-1β expression by LPS-stimulated microglial cells by Af extract. Microglial cells (5 × 106 cells) were treated with 100 μg/mL of Af extract, followed by stimulation with LPS (4.5 ng/mL) for 20 h. The products following RT-PCR were separated on agarose gel. A. The gel represents one of three different experiments with similar results. The levels of β-actin transcripts were similar in all samples. B. Data represent the means ± SD of three independent experiments (n = 3). The levels of IL-1β transcripts were normalized to the levels of α-Tubulin transcripts.