PROM1 and neoplasm: While only 3 of 7 mice injected with the mock transfected EpCAM−/CD133− cells exhibited a tumor formation, the tumor incidences were 6 out of 7, and 7 out of 7 for the mice injected with EpCAM+/CD133+ cells and mice injected with EpCAM−/CD133− cells overexpressing KLF4, respectively, suggesting that a KLF4 overexpression restores the tumorigenic potential (Figure 4A).