Human Embryonic Stem Cells (IMAGE) University of California - Santa Barbara Caption Human embryonic stem cells are poised between a proliferative state with the potential to become any cell in the body and a differentiated state with a more limited ability to proliferate. To maintain this delicate balance embryonic stem cells express a set of factors, including OCT4, SOX2, and KLF4, to control multiple genes that sustain the proliferative pluripotent state. These genes can be repressed by a tiny RNA called miR-145, and in turn, one of the transcription factors, OCT4, can repress miR-145. Thus, a double negative feedback loop sets the delicate balance. Credit None Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.