ALDH1A1 and hepatocellular carcinoma: Identification of CSCs from human HCC tumors and human HCC cell lines has been performed using various CSC surface biomarkers, including CD90+, CD44+, epithelial cell adhesion molecule (EpCAM+), CD133+, OV6+, aldehyde dehydrogenase 1 (ALDH1+), and alpha-fetoprotein (AFP+) [5, 7, 9, 10].