CD44 and hepatocellular carcinoma: Although there is no universal CSC marker that can be used to identify the CSCs of HCC, studies have shown some of the main surface markers that can identify liver CSCs, including epithelial cell adhesion/activating molecule (EpCAM) (CD326), cluster of differentiation 90 (CD90), CD44 and CD133 [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39].