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