The NF-κB p105/p50 Colorimetric Cell-Based ELISA Kit provides a lysate-free, convenient, and high-throughput approach for sensitive detection of NF-κBp105/p50 protein expression profile in cells. The kit can be used for measuring the relative amounts of NF-κBp105/p50 in cultured cells as well as screening for the effects that various treatments, inhibitors (ie siRNA or chemicals), or activators have on NF-κBp105/p50.