This is a key step of extravasation in hematogenous metastasis.5 CTC extravasation typically occurs in small capillaries, where cancer cells are arrested by the endothelium via interaction with a wide range of adhesion molecules of ECs, including E-selectin, ICAM-1 (intercellular-adhesion molecule-1) and VCAM-1 (vascular cell adhesion molecule-1), through their cognate ligands.6,7 E-selectin is expressed exclusively by ECs in rapid response to inflammatory stimuli (e.g., TNF-α and IL-1β). Here, VCAM1 is linked to cancer.