Time course of activation of integrated reporter genes in RAW264 cells. Pooled stable transfectants of RAW264 cells, with either the ELAM or IL-12 promoter driving firefly luciferase, cotransfected with the IL-1β promoter driving renilla luciferase, were cultured overnight as described in Materials and Methods. Where the cells were washed, the medium was aspirated, and replaced immediately with warm medium at time zero. A typical experiment of three is shown. Results for ELAM and IL12 promoters are the average of duplicates that differ by less than 10% from the mean. In the case of the IL-1β data, the results are the average of 4 datapoints obtained with the two separate pooled transfectant lines in the same experiment.