Fig. (2) Destabilized luciferase genes increase the reporter response and reduce the assay time to reach maximum induction. luc2, firefly luciferase; luc2P, firefly luciferase with hPEST sequence; luc2CP, firefly luciferase with hCL1 and hPEST sequences. HEK293 cells transiently expressing various versions of SRE- or SRF-RE- reporters (luc2, luc2P or luc2CP) were serum starved, induced with 20% FBS plus 10ng/ml PMA for SRE (2B, 2D), or with 20% FBS for SRF-RE (2C, 2E) for 2-8 hours. Cells not induced after serum starvation were used as control (uninduced). Firefly luciferase activity (RLU) were determined using One-Glo assay system and measured on the GloMax 96 multiplate luminometer. (2B, 2C) Firefly luciferase activity (RLU) and fold of induction measured after six hours of induction. (2D, 2E) Time course of fold of induction of SRE- and SRF-RE measured every two hours for 8 hours after induction.