Wikipedia
Chemical Activated LUciferase gene eXpression (CALUX) is a bioassay used in the detection of specific chemicals in samples. It consists of a modified cell line that has a DNA construct with a luciferase reporter gene in conjunction with response elements that can induce transcription of the inserted gene for the light-generating enzyme. The response elements can be varied in order to provide binding sites for other receptors that relate to a chemical of interest that is wished to be detected. The CALUX bioassay has thus been redesigned to detect certain chemicals of interest. Most applications have been oriented in detecting environmentally harmful chemicals like environmental hormones.
CALUX is an effect based screening method as it measures the total effect ligands (from a sample) have on a receptor. Unlike chemical analysis, CALUX is thus able to measure all activity on the receptor of interest. This also includes unidentified congeners of certain ligands.