THY1 and hepatocellular carcinoma: A recent study demonstrated that the CSC marker CD90, a THY1 gene product, was important for the cell cycle, migration, invasion, and sphere-forming ability of HCC cells.19 The observed SIX1-dependent effects in the self-renewal capacity prompted the analysis of the CD90 cell population in shSIX1-SNU398 and control-SNU398 cells by flow cytometry; the knockdown of SIX1 significantly decreased the CD90+ subpopulation in shSIX1-SNU398 cell clones (35.1%) compared with the control-SNU398 cell clones (65.5%) (Figure 4C).