Fig. 4. NO-mediated cyclic GMP signaling is not involved in the suppression of Notch signaling. (A) NIH3T3 cells were transfected with the 4xCSL-Luc promoter, plus/minus Notch1-IC, along with lacZ. The cells were pre-treated with 100 µM ODQ for 1 hour prior to treatment with 200 µM SNAP, or were exposed to 100 µM 8-Bromo-cGMP for 8 hours. (B) Rat primary alveolar macrophage cells were transfected for 24 hours with the indicated combinations of expression vector for 4xCSL-Luc and Notch1-IC along with lacZ. The cells were pre-treated with 100 µM ODQ for 1 hour prior to treatment with exposure to 5 µg/ml LPS for 24 hours, or were exposed to 100 µM 8-Bromo-cGMP for 24 hours. The cells were lysed and assayed for luciferase activity. The activity of the luciferase reporter in each of the samples was then normalized according to the β-galactosidase activity measured in the same sample. These results represent the means ± average deviation of triplicates from one of three independent experiments.