Fig 5. Sensitivity of the mitotic checkpoint response.

(A) Steady state values for APC/C^Cdc20 (normalized to total Mad) when varying the rate of MCC1 formation for models (i), (ii), and (iii). It is reasonable to assume that the association rate for an active checkpoint lies between 5 and 500 (in units of 1/min*[total Mad]) [14, 42]. (B) By decreasing the association rate k_{ass_AMCC2} of reaction 3 in the sequential inhibition model (top), the funneling effect is weakened, as shown by checkpoint response curves for different values of k_{ass_AMCC2} (bottom). The same effect can be seen in the competitive and combined models, which share the same funnelling effect with the sequential inhibition model.