The InCELL Hunter technology measures compound binding to an intracellular target by detecting changes in protein stability. In this assay, the target is fused to the enhanced ProLabel®(ePL) enzyme fragment and expressed in the selected cell background. The amount of fusion protein is quantified through the addition of cell lysis buffer and a complementary enzyme acceptor fragment (EA). The two enzyme fragments complement to form a functional enzyme that is capable of hydrolyzing substrate and generating a chemiluminescent signal. These cells have been modified to prevent long term propagation and expansion using a proprietary compound that has no apparent effect on assay performance.