KLF4 and hepatocellular carcinoma: To further investigate whether Klf4 plays critical roles in tumor-associated phenotypes in HCC cells, the murine HCC cell line MM189 was infected with a retroviral vector encoding mouse Klf4 (MM189 PB-Klf4 cells), or empty vector (MM189 PB cells), and ectopic Klf4 expression confirmed by immunoblot assay (Figure 1A).