Later on, we will extend this simple model to more realistic cases with multiple cell types and with multiple compartments, where multiple point mutations can successively accrue to confer resistance to exceedingly high drug concentrations [54].

Let us now specifically incorporate into the simple model a Hill function that describes concentration-dependent killing efficacy of drugs (see Materials & Methods).

We also extend the simple model to more general cases with multiple cell types and with multiple compartments (see detailed mathematical description in 81 Text).

In our opinion, this meticulous structure of the energy landscape for our simplified model is of general interest to other cell cycle dynamics, and the proposed methods can be applied to study similar biological systems.

In our simplified model describing the essential dynamics of the yeast cell cycle process, we assumed the “domino” mechanism of cell cycle regulation, which is different from the previous Tyson’s model [42] and its landscape [9].

Most of the insights we gained studying this simple model are independent of the number of dimensions and the specific formulation of the model, and therefore will be valuable to other systems and studies.