The p70 S6 Kinase (Phospho-Thr389) Colorimetric Cell-Based ELISA Kit provides a lysate-free, convenient, and high-throughput approach for sensitive detection of p70 S6 Kinase (Phospho-Thr389) protein expression profile in cells. The kit can be used for measuring the relative amounts of p70 S6 Kinase (Phospho-Thr389) in cultured cells as well as screening for the effects that various treatments, inhibitors (ie siRNA or chemicals), or activators have on p70 S6 Kinase (Phospho-Thr389).