Figure 4
From: A gene expression system offering multiple levels of regulation: the Dual Drug Control (DDC) system
Inducing gene expression at two tiers. Target genes are modeled by the hGH gene (ZFHD-dependent transactivation, expression responsive to dimerizer only; scale is on the right Y-axis) and the SEAP gene (tTA-dependent transcription expression responsive to dimerizer AND tetracycline; scale is on the left Y-axis). All cells contain pC4N2-RHS/ZF3, pZ12I-hGH-2, pZBS-Tet-OFF, and pBI-EGFP-SEAP. See Results for details of manipulations A-D; briefly, A was grown in continuous dimerizer-/tetracycline+; B-D were initially in dimerizer+/tetracycline+. At 48 hours after transfection with plasmids, A and B were harvested, while C and D were grown for 48 more hours in dimerizer+/tetracycline+ (C) or dimerizer+/tetracycline- (D) medium before harvesting. Results of one typical experiment, with four parallel transfections for each data point, are shown. Each experiment was repeated at least three times.