Semiquantitative RT-PCR analysis of COX-2 mRNA. Representative semi-quantitative RT-PCR analysis of COX-2 mRNA in microglial cultures, subcultured as in Fig. 3, pre-treated with nicotine (Nic, 0.1–1 μM) for 30 min and stimulated for 7 h (A, upper panels) or 24 h (B upper panels) with LPS (10 ng/ml). The amount of COX-2 mRNA, expressed as the ratio of densitometric measurement of the sample to the corresponding internal standard (β-actin), is shown in the lower panels. Data are shown as mean ± SEM for 3 to 4 independent experiments, with the exception of 1 μM nicotine, panel A (n = 2); all run in duplicate. * p < 0.05 vs fcs; **p < 0.05 vs fcs.