CD44 and cancer: To characterize the epithelial characteristics or phenotypes of these two series of cell lines, we performed western blot to assess the expression of epithelial cell–cell adhesion molecules E-cadherin [28] and EpCAM [29], the intermediate filament cytokeratin 7 (CK7) [30], and the cell surface transmembrane glycoprotein widely implicated as cancer stem cell marker, CD44 [31].