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