ICAM3 and cancer: Of the 5 identified intercellular CAMs in humans, ICAM-3 is best known for its constitutive expression on human leukocytes and while there is little evidence for its expression on endothelial cells in vitro [49], it has been identified on vessels in benign and malignant tumors [50], [51], [52], [53], [54], [55] while weakly or not at all found on endothelial cells during inflammation [53], [56].