A. In the presence of Doxycycline (Dox), the tetracycline-regulated transactivator (tTA) is unable to bind to the hCMV*-1 promoter (Tetracycline response element followed by the minimal promoter of the human cytomegalovirus immediate early gene) and initiate downstream gene expression.
B. Once the drug is removed from the tissue culture medium, the tTA binds the promoter and the dnTcf4 and Venus proteins are transcribed.
C. Control cells inducibly express Venus, but lack the dnTcf4 cDNA.