Sialyl Lewis x (sLe^x) and sialyl Lewis a (sLe^a)   glycans are expressed on highly metastatic colon cancer cells. They   promote extravasation of cancer cells and tumor angiogenesis                       via interacting with E-selectin on endothelial   cells. Recently, epithelial–mesenchymal transition (EMT) has been noted   as                       a critical phenotypic alteration in metastatic   cancer cells.