THY1 and hepatocellular carcinoma: Xenotransplantation and fluorescence-activated cell sorting (FACS) experiments have identified key indicators for CSCs in HCC, which can be categorized into intracellular indicators, like cytokeratin 19 (CK19), and surface indicators, such as CD13, CD24, CD44, CD47, CD90, CD133, and epithelial cellular adhesion molecule (EpCAM)8.