Fig. 1.

The metastatic cascade. EMT programs are involved in early steps of the metastatic cascade, where they enable the invasion into the stroma (depicted in orange, underdlying the basement membrane in blue) and translocation of carcinoma cells (depicted in blue, changing to red when undergoing an EMT) to distant parenchyma (green). EMT programs are dynamically regulated and, during the last step of the metastatic cascade, colonization, carcinoma cells are thought to switch back to an epithelial state (blue cells) through the reverse process, mesenchymal–epithelial transition (MET).