Before revision:  I demonstrate this by an example of two different models of lac operon . 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:  I demonstrate this by an example of two different models of lac operon , where TMG/lactose uptake is driven by a Michaelis-Menten enzymatic process. We show that as a consequence of the steady state displacement due 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 .