CD90 (Thy-1), which was first reported in hematopoietic [24] and mesenchymal [25] stem cells, has also been identified as an oval cell marker [26] and is expressed in hepatic cancer stem cells of human liver cancer [27] as well as in hepatic stem/progenitor cells during liver development, but is rarely detected in adult liver cells [22, 28]. The gene discussed is THY1; the disease is liver cancer.