Figure 3.

EMT in systemic transport and extravasation. Experimental and clinical samples have revealed an EMT signature in CTCs. This signature provides a possible biomarker to monitor tumor progression and/or therapeutic response. Experimental evidence suggests that platelets play a critical role in maintaining EMT activation in CTCs by providing the TGF-β signal. Furthermore, studies suggest that activation of EMT promotes microtentacle formation that allows tumor cell attachment to the endothelium and promotes cell survival. In order to extravasate at distant sites, tumor cells maintain an EMT phenotype and express cellular protrusions that allow extravasation, which is mediated by β1 integrin signaling.