POU5F1 and cancer: In recent years, induced pluripotent stem cells (iPSCs) have been in vitro generated from different cell types of several species, including mouse, rat, rabbit, sheep, pig, monkey and human, following ectopic expression of the transcription factors Oct4 and Sox2, combined with either Klf4 and c-Myc or Lin28 and Nanog [4–24], suggesting an in vitro powerful system and tool to in vitro examine the reprogramming mechanisms of somatic cells and cancer cells.