Figure 1. Systems biology identifies a promising target for reverse aging in human dermal fibroblasts. Inhibition of PDK1 reverts senescent cells (left) to quiescent cells (right) without inducing uncontrolled proliferation in human dermal fibroblasts. Nodes are colored according to whether PDK1 inhibition from cellular senescence attractor state increases (red) or decreases (blue) the node activity, and edges that constitute the core positive feedback loop are colored depending on their signs of signal flows; positive (red) or negative (blue) (see An et al.  for more details). Three nodes that constitute minimal feedback vertex set are marked by yellow stars.