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