The Notch CSL Reporter - HEK293 cell line contains the firefly luciferase gene under the control of Notch-response elements (CSL responsive elements) stably integrated into HEK293 cells. Transfection of this cell line with a Notch expression vector and activation of the Notch pathway leads to expression of luciferase reporter. This cell line is validated with a Notch1DelE expression vector, which is constitutively processed by γ-secretase, leading to the release of NICD and the expression of luciferase.