Kinetics of IL-8 mRNA expression with Et-1 treatment by RPA. Confluent CNS-EC cultures were treated with Et-1 (10⁻⁷ mol/L) for 0.5, 1, or 4 hours or left untreated. Subsequently, total RNA was isolated from the cells and probed with³²P-labeled riboprobes for IL-8 or GAPDH. The results were visualized by autoradiography. The protected size corresponding to IL-8 (181 bp) and GAPDH (96 bp) is shown.