Time and dose response kinetics of luciferase in response to GS-E. (A) Cell clone MBT-2+RHeoSwitch-2+luc-5B3 was treated with GS-E and cells were harvested at different times to determine the time course of gene induction. At each time point, the control and treated cells were collected in passive lysis buffer and dual luciferase assays performed. Data were plotted as a GS-E (RLU1/RLU2)/ Control (RLU1/RLU2) ratio (as in Table 1) fold induction over the 0 time point which was set empirically as 1. The internal control, Renilla luciferase, increase steadily with time, reflecting the increase in cell number, but the increase was the same with DMSO or GS-E treatment (raw data not shown but effect accounted for in the calculation as defined above). (B) The sensitivity of the gene expression system to varying doses of GS-E was determined by treating duplicate samples of clone MBT-2+RHeoSwitch-2+luc-5B3 with varying concentrations of GS-E for 24 hours and dual luciferase assays and data analysis were performed on the cell lysates as described in (A) above.