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. 2012 Jul 20;2012(1):10. doi: 10.1186/1687-4153-2012-10

Figure 4.

Figure 4

Effects of the modulation of the negative feedback on Cdc25 (reaction constantc34). The figure shows the simulated dynamics of cAMP (left) and Ras2-GTP (right) resulting from a PSA-1D on the value of the reaction constant that modulates the phosphorylation of Cdc25 by means of active PKA. The varied parameter is constant c34 (see Table 1), within the interval [1.0×10−3, 1.0×103], being 1.0 the reference value (represented with the black thick line). Stable oscillations occur in both cAMP and Ras2-GTP dynamics, for any value of the reaction constant, regardless of the magnitude of the feedback exerted by PKA on Cdc25. For larger values of the constant, namely c34 greater than 1.0, the only effect is a reduction in the amount of cAMP and Ras2-GTP (whose average values are reduced from around 40,000 to 35,000 molecules, and from around 270 to 130 molecules, respectively) and an increase of about fifty per cent in the frequency of oscillations with respect to the reference value.