Incorporation of labeled glucose or fructose as a function of concentration of the labeled sugar and effect of presence of other (cold) sugar. Incorporation of labeled sugar in the absence of the other is shown by the blue symbol and the unbroken gray line. When the other (unlabeled) sugar is added there is a shift in the incorporation as shown by the red symbol and the gray broken line). All the effects are enhanced upon addition of insulin (heavy black lines). Figure redrawn from Parniak & Kalant .