Figure 2.

Layout of an epithelial-mesenchymal transition (EMT) transition process and forward migration of cells. Epithelial cells are bound together by tight junctions, adherens junctions, and desmosomes. The adherens junctions are cadherin-based and actin filament-associated cell-to-cell junctions that are composed of defined protein complexes. Epithelial cells are tightly secured to the basement membrane via highly specialized integrin-mediated attachment structures. Signaling pathways are said to trigger the EMT process—propagated by various EMT-TFs, such as ZEB, SNAIL, and TWIST that curb gene expression (listed in the blue box) related with the epithelial state and induce expression of genes associated with the mesenchymal state (listed in the pink box). Mesenchymal cells contain vimentin-based intermediate filaments and use integrin-containing focal adhesions to attach to the ECM. In contrast to epithelial cells, mesenchymal cell migration presents a leading and trailing edge and an extensively reorganized cytoskeleton. Lamellipodia is formed by polymerization of actin by the WAVE-Arp2/3 nucleation mechanism.