YY2 and hepatocellular carcinoma: YY2 overexpression clearly decreased the number of tumor spheres formed by HCC‐LM3 and MHCC‐97H and cells (Figure 2C), as well as the frequency of liver CSCs in the spheres from 1:4 to 1:13 (Figure 2D) and 1:11 (Figure S3A, Supporting Information), respectively.