Figure 1.

During tumor progression, epithelial tumor cells undergo partial EMT through their crosstalk with contextual signals, including growth factor signaling, inflammatory cytokines, immune environment and hypoxia. Concomitantly, these tumor cells within intermediate states gain the ability of motility while remaining cell-cell junction and expressing E-cadherin. After complete EMT, the intermediate tumor cells lose their epithelial junctions, their cytoskeleton reconstructed and vimentin filaments were generated instead of E-cadherin. After intravasation and extravasation through blood vessel, the EMT positive tumor cells arrive at their target organ, and they have to experience MET to accomplish colonization.