The STAT5A/B Cell-Based ELISA Kit is a convenient, lysate-free, high throughput and sensitive assay kit that can monitor STAT5A/B protein expression profile in cells. The kit can be used for measuring the relative amounts of STAT5A/B in cultured cells as well as screening for the effects that various treatments, inhibitors (ie. siRNA or chemicals), or activators have on STAT5A/B.