Applying this to the cancer stem cell concept suggests that CSCs can exist as two interchangeable populations and Biddle, et al.3(2011) confirmed that CSCs form a dynamic cell population that uses EMT and MET to switch backwards and forwards between a proliferative epithelial phenotype (EPI-CSC; CD44highESAlow/+ALDH+) and a migratory mesenchymal phenotype (EMT-CSC; CD44highESAlow/, ALDH-) (Figure 3). Here, LDHA is linked to cancer.