The inducible promoter PTRE3G provides for very low basal expression and high maximal expression after induction. It consists of 7 repeats of a 19 bp tet operator sequence located upstream of a minimal CMV promoter. PTRE3GV is a version of PTRE3G that was modified at Clontech for higher performance in lentiviruses and retroviruses. In the presence of Dox, Tet-On 3G binds specifically to PTRE3GV and activates transcription of the downstream GOI. PTRE3GV lacks binding sites for endogenous mammalian transcription factors, so it is virtually silent in the absence of induction. pLVX-TRE3G-ZsGreen1 is an HIV-1-based, inducible lentiviral expression vector that allows the simultaneous expression of ZsGreen1 and your protein of interest in virtually any mammalian cell type, including primary cells.