FIGURE 6.
p53 pulses. A, shown is a bifurcation diagram of [p53*] versus [ATM*]. There is a Hopf bifurcation (HB). If [ATM*] is limited in a region between 2.9 and 4.8, the p53* level oscillates between the maximum and minimum of the limit cycle (open circle). B, shown is a phase diagram of [p53*] versus [ATM*]. When ATM is inhibited by Wip1, it switches between low and high levels; accordingly, the p53 level also undergoes oscillations. Displayed are time courses of [Aktp], [Mdm2c], [Mdm2n], and [p53*] at DIR = 3 (C) or 5 Gy (D).