pRNATin-H1.2/Hygro is a GenScript inducible siRNA expression vector. The H1.2 promoter is an engineered inducible promoter* containing a tetracycline operator (TetO1). The Tetracycline operator itself has no effect on expression. When the tetracycline repressor (TetR) is present, it effectively binds the TetO1 and blocks the transcription. In the presence of tetracycline or doxycycline, the inducer binds TetR and causes the TetR protein to release the TetO1 site, and derepressing the transcription from the H1 promoter.