Identifying (un)controllable dynamical behavior in complex networks
Fig 3
(Top) The network diagram and stable motif for the T-cell signaling model of [37] with all sources saturated.
In the stable motif diagram, node shape and color indicate whether an upper or lower bound is specified (as indicated by the node labels). The variables constrained by the stable motif cannot leave the region of state-space specified by the stable motif once it has been entered. This remains true even when TCRp, which regulates ZAP, but is not included in the stable motif, is subjected to external control, provided it remains within the bounds considered when constructing the expanded network (between 0 and 1 in this case, though a similar result can be obtained for 0 ≤ TCRp < ∞). This robustness is illustrated in the bottom panel, in which solid colored lines indicate dynamic variable values that are constrained by stable motif thresholds (dashed lines). The black dotted line is the TCRp value and is subject to different external controls in panel of sub-figure (b).