The Cytochrome P450 2C8/9/18/19 Colorimetric Cell-Based ELISA provides a lysate-free, convenient, and high-throughput approach for sensitive detection of CytochromeP4502C8/9/18/19 protein expression profile in cells. The kit can be used for measuring the relative amounts of CytochromeP4502C8/9/18/19 in cultured cells as well as screening for the effects that various treatments, inhibitors (ie siRNA or chemicals), or activators have on CytochromeP4502C8/9/18/19.