Figure 1. TetR-based two-vector system for efficient generation of dose-responsive Tet-On cell lines.

A) Maps of the two lentiviral vectors required for doxycycline-dependant transgene regulation. The TetR repressor is expressed through the constitutive SFFV promoter, highly active in most cell types, including hematopoietic cells. The second lentiviral vector contain the doxycycline-responsive CMV-TetO promoter(Yao et al. 1998) driving the expression of eGFP. 293T, primary human fibroblasts (HFFs) and K562 cells were co-transduced with STetR and CTetOE lentiviral vectors at high MOI and analyzed by fluorescence microscopy (B) or flow cytometry (C) in the absence (–Dox) or presence (+Dox) of 10 ng/ml of doxycycline. D) Doxycycline responsiveness (0.001 µg/ml, 0.01 µg/ml and 0.1 µg/ml as indicated) of the Tet-ON HFF cell line derived by cotransduction with STetR and CTetOE LVs.