Before revision:  To demonstrate this, we show that for the distributive phosphorylation of a protein at two binding sites multistationarity is only possible if the total concentration of the substrate is larger than either the  concentration of the kinase or the  phosphatase.
After revision:  To demonstrate this, we show that for the distributive phosphorylation of a protein at two binding sites multistationarity is only possible if the total concentration of the substrate is larger than either the concentration of the kinase or the total concentration of the phosphatase.