EPCAM and cancer: MET CSCs actively self-renew and express aldehyde dehydrogenase (ALDH, a marker independently identified as a CSC indicator in several types of cancer (Ginestier et al., 2007; Clay et al., 2010; Silva et al., 2011; Kryczek et al., 2012), epithelial cell adhesion molecule (EpCAM, the same molecule that forms the basis for the capture of CTCs by CellSearch and the CTC- and HB-chips), and CD49f (α6 integrin subunit) in contrast to quiescent yet invasive CD44+/CD24-/EpCAM-/CD49f+ EMT CSCs (Liu et al., 2012).