  We present the epithelial-to-mesenchymal transition (EMT) from two
perspectives: experimental/technological and theoretical. We review the state
of the current understanding of the regulatory networks that underlie EMT in
three physiological contexts: embryonic development, wound healing, and
metastasis. We describe the existing experimental systems and manipulations
used to better understand the molecular participants and factors that influence
EMT and metastasis. We review the mathematical models of the regulatory
networks involved in EMT, with a particular emphasis on the network motifs
(such as coupled feedback loops) that can generate intermediate hybrid states
between the epithelial and mesenchymal states. Ultimately, the understanding
gained about these networks should be translated into methods to control
phenotypic outcomes, especially in the context of cancer therapeutic
strategies. We present emerging theories of how to drive the dynamics of a
network toward a desired dynamical attractor (e.g. an epithelial cell state)
and emerging synthetic biology technologies to monitor and control the state of
cells.
