Mathematically, the inverse problem is formulated as an nonlinear optimization problem with equality constraint on the x-abscissa of the G1/S point, SN1. The bifurcation diagram corresponding to the solution (k25 = 1.182, φE2F1 = 0.0992, φAP-1 = 0.0109) is given in Figure 13. Row 2 of Table 3 summarizes the number of iterations required.