KLF4 and cancer: For instance, Oct4 drives the transformation potential of testicular germ cells [6]; Sox2 is an amplified lineage-survival oncogene in lung and esophageal squamous cell carcinomas [7, 8]; Klf4 can function as a dominant oncogene, as it is frequently overexpressed in human breast tumors and squamous cell carcinomas [9]; and c-Myc is a well-known gene deregulated in multiple human cancers [10].