The p57 Kip2 Colorimetric Cell-Based ELISA Kit provides a lysate-free, convenient, and high-throughput approach for sensitive detection of p57Kip2 protein expression profile in cells. The kit can be used for measuring the relative amounts of p57Kip2 in cultured cells as well as screening for the effects that various treatments, inhibitors (ie siRNA or chemicals), or activators have on p57Kip2.