Release of translational blockade imposed by the TNF 3′-UTR is prevented by dominant inhibitors of
RAW 264.7 cells were cotransfected with a reporter construct in which a CMV promoter was used to drive transcription of a CAT mRNA in which the TNF 3′-UTR was appended, together with empty vector (control) or vectors encoding dominant inhibitors of ras or raf-1. Cultures were induced with LPS at a concentration 1 µg/ml 24 hr after transfection, and cells were harvested for CAT assay 48 hr after transfection. Quantitation of CAT activity, and calculation of the induction ratio, was performed using a phosphorimager. CM, chloramphenicol; AcCM, acetylated forms of chloramphenicol.