Effects of dominant inhibitors of ras and raf-1, and the active raf-BXB protein, on responses of the TNF promoter to LPS
RAW 264.7 cells were cotransfected with expression constructs encoding each of these proteins, or with an empty vector (control), and with a TNF promoter-CAT construct. Cells were stimulated with LPS at a concentration of 1 µg/ml 24 hr after transfection and harvested and lysed for determination of CAT activity 48 hr after transfection, as described in Materials and Methods. The ratio of CAT activity in stimulated versus unstimulated cells (LPS induction ratio) was calculated on the basis of phosphorimager analysis. CM, chloramphenicol; AcCM, acetylated forms of chloramphenicol.