Serum variation influences cell cycle dynamics. A color-code identical to that of Figure 2 panel C1 was defined for serum variation (see Table 2), and model outputs were then consequently colored. Panels A and B report the colored visualizations of CycD and E2F, respectively. CycD levels increase with serum concentration: colors are well clustered and stratified in the order expressing a serum increase (black-blue-red-green). E2F distribution, instead, exhibits a bimodal dependence on serum concentration: low E2F state is mainly characterized by black and blue lines (low serum concentration), while the high state corresponds to green lines (high serum concentration).