Bifurcation diagrams for the Hill coefficients. (A)The single parameter bifurcation diagram of n, n1, n2 and n3, with an increase of the parameter n the concentration of CDK1 decreases slightly but the concentration of CDK1 increases gradually with increases in n1, n2 and n3. The changing of n2 is very sensitivity to the concentration of CDK1. (B)(C) and (D) are two-parameter bifurcation diagrams for each pair among n, n1, n2 and n3, respectively. I: stable region, and II and III: oscillation regions.