Fig. (3) Use of Metridia luciferase in single or multiplexed applications with another secreted bioluminescence reporter. Panel A. Monitoring promoter activation using the sequence-optimized secreted Metridia luciferase reporter. HeLa cells were transiently transfected with a vector construct containing the NFκB response element driving the expression of sequence-optimized secreted Metridia luciferase. 24 hr after transfection, the media was removed and replaced by media with or without TNF-α (100 ng/ml) to activate the NFκB signal transduction pathway. Six hr after addition of TNF-α, samples of the media were removed and analyzed for Metridia luciferase activity. The fold induction was calculated for different time points following the addition of substrate. Panel B. Monitoring the activities of two promoters using two secreted reporters, secreted Metridia luciferase and SEAP.