RU486 inhibition of Dex-induced apoptosis and signaling pathways. (A) Effect of RU486 (10⁻⁶ mol/L) on Dex-induced apoptosis as detected after an 18-hour culture. Percentage numbers of hypodiploid nuclei are reported for each condition. The results are representative of one out of three separate experiments. (B) Effect of RU486 on Dex-induced acidic (left) and neutral (right) SMase activities after 15 or 120 minutes of Dex treatment, respectively. Hydrolyzed SM was quantitated and expressed as picomoles/10⁶ cells. Mean values of three different experiments in duplicate are reported. SD, less than 10% of the mean values, are omitted for clarity. (C) Effect of RU486 on Dex-induced PI-PLC activity at 5 minutes. Cell extracts were reacted with radiolabeled PI vesicles, and then DAG released was separated by TLC, visualized by autoradiography, scraped from the plate, and counted by scintillation counting. PI-PLC activity is expressed as picomoles DAG/10⁶ cells. Mean values of three different experiments in duplicate are reported. SD, less than 3% of the mean values, are omitted for clarity.