The Opioid Receptor-delta Colorimetric Cell-Based ELISA Kit provides a lysate-free, convenient, and high-throughput approach for sensitive detection of OpioidReceptor-delta protein expression profile in cells. The kit can be used for measuring the relative amounts of OpioidReceptor-delta in cultured cells as well as screening for the effects that various treatments, inhibitors (ie siRNA or chemicals), or activators have on OpioidReceptor-delta.