Thus, it is likely that during non-functionalization and DNA deletion that follows a WGD, the trio of M, N and the protease-encoding genes will tend to be retained. Let us now explore what would happen after a hypothetical volumetric contraction due to a ‘massive’’ DNA deletion. Under this assumption, if M is expressed in response to a signal, the kinetics of formation of MM before reaching the steady state is altered as compared to the initial autotetraploid state, even if all interacting genes are retained. Figure 2 shows the kinetics of an extreme situation where all duplicates have been deleted but those involved in the system MM-N,Ponatinib compared to the initial one. Both systems attain the same concentration of MM at the steady state. However, this process is faster in the case of ‘WGD+D’. Indeed, to attain the halfpoint of the steady-state concentration of MM, the initial cell requires twice as much time as the one in the situation WGD+D. In turn, N, which acts as a monomer, attains the steady state much more rapidly in both systems. Such a kinetic difference predicted for MM can be crucial, especially in signal transduction cascades and other cellular pathways where the kinetics, and time delays, are important. This holds also for cases involving a slow/progressive deletion process. Increases of the concentrations of gene products involved in cellular circuits can also upset the regulation of the latter and change their dynamics. To explore such effects we turn to the minimalist model of a mitotic clock ), which reproduces qualitatively some features of the cell cycle. Again, we will consider an extreme scenario in which,AG-013736 after a WGD and subsequent DNA deletion, only genes involved in the model circuit are left duplicated. This doubles the concentrations of the corresponding gene products. Figure 3 shows that these conditions drive the circuit dynamics to a potentially unsustainable regime, namely to doubling the frequency of the cell-cycle. The examples above show that even if dosage balance is maintained stricto sensu, a potential volumetric contraction owing to DNA deletions might be harmful.