Schematic representation of the model. The figure shows, schematically, the components and interactions included in the model. Transcription of mdm2 and subsequent translation to the Mdm2 protein are described by the rate constants k
, respectively. β represents the rate of spontaneous degradation of the Mdm2 mRNA. Two rate constants describe complex formation (k
) and breakup (k
). p53 is assumed to be produced at a constant rate σ. Degradation of p53 occurs at the rate δ when it is Mdm2-mediated, and at the rate α when it is Mdm2-independent. Finally, we assume that the Mdm2 degradation rate, γ, is independent of whether it is bound to p53 or not.