The Histone H2A.X (Phospho-Ser139) Cell-Based ELISA Kit is a convenient, lysate-free, high throughput and sensitive assay kit that can monitor Histone H2A.X (Phospho-Ser139) protein expression profile in cells. The kit can be used for measuring the relative amounts of Histone H2A.X (Phospho-Ser139) in cultured cells as well as screening for the effects that various treatments, inhibitors (ie. siRNA or chemicals), or activators have on Histone H2A.X (Phospho-Ser139). Species Reactivity: human, mouse, rat. Range: > 5000 Cells. Sensitivity: >5000 cells