Use KeyTec® Ultra Luciferase Detection Kit (no DTT) to detect the overexpression of Firefly luciferase in the HEK293 cell line. The results showed a linear relationship between the luminescence signal and the number of cells. HEK293 cells, cultured in DMEM medium with 10% FBS, were serially diluted two-fold, starting from 50,000 cells per well in a 96-well plate. Perform the assay according to the procedure outlined in “Assay Procedure”. Five minutes after adding the reagent, measure the luminescence signal using the Envision's Luminescence program. (Example program details include Mirror: Luminescence, Em filter: Luminescence 700, Measurement height: 6.5 mm, and Measurement time: 1 s).