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 is quantified through the addition of substrate and complementary enzyme acceptor fragment (EA). The small size, but robust activity of the ePL tag makes it an ideal fusion partner. The small disordered peptide has minimal effects on target half-life, and generates high levels of enzyme activity, resulting in a sensitive measurement of protein levels.