PROM1 and hepatocellular carcinoma: Subsequently, other specific surface markers such as cluster of differentiation 133 (CD133), epithelial cell adhesion molecule (EpCAM), CD90, CD44, CD24, CD13, OV6 and their co-expression, as well as aldehyde dehydrogenase (ALDH) activity are applied to isolate or enrich hepatic CSCs from HCC cells [21].