Before revision:  The bistable switch responds to fluctuations in extracellular TMG/lactose concentration  in an asymmetric manner because of the displacement of its bistability region to the right: As noise intensity increases, uninduction becomes easier and induction becomes more difficult .
After revision:  The bistable switch responds to fluctuations in extracellular TMG/lactose concentration in an asymmetric manner because of the displacement of its bistability region to the right: As noise intensity increases, switching off lactose metabolism becomes easier and induction becomes more difficult .