<P> Induced pluripotent stem cells, commonly abbreviated as iPS cells or iPSCs, are a type of pluripotent stem cell artificially derived from a non-pluripotent cell, typically an adult somatic cell, by inducing a "forced" expression of certain genes and transcription factors . These transcription factors play a key role in determining the state of these cells and also highlights the fact that these somatic cells do preserve the same genetic information as early embryonic cells . The ability to induce cells into a pluripotent state was initially pioneered in 2006 using mouse fibroblasts and four transcription factors, Oct4, Sox2, Klf4 and c - Myc; this technique, called reprogramming, earned Shinya Yamanaka and John Gurdon the Nobel Prize in Physiology or Medicine 2012 . This was then followed in 2007 by the successful induction of human iPSCs derived from human dermal fibroblasts using methods similar to those used for the induction of mouse cells . These induced cells exhibit similar traits to those of embryonic stem cells (ESCs) but do not require the use of embryos . Some of the similarities between ESCs and iPSCs include pluripotency, morphology, self - renewal ability, a trait that implies that they can divide and replicate indefinitely, and gene expression . </P> <P> Epigenetic factors are also thought to be involved in the actual reprogramming of somatic cells in order to induce pluripotency . It has been theorized that certain epigenetic factors might actually work to clear the original somatic epigenetic marks in order to acquire the new epigenetic marks that are part of achieving a pluripotent state . Chromatin is also reorganized in iPSCs and becomes like that found in ESCs in that it is less condensed and therefore more accessible . Euchromatin modifications are also common which is also consistent with the state of euchromatin found in ESCs . </P> <P> Due to their great similarity to ESCs, iPSCs have been of great interest to the medical and research community . iPSCs could potentially have the same therapeutic implications and applications as ESCs but without the controversial use of embryos in the process, a topic of great bioethical debate . In fact, the induced pluripotency of somatic cells into undifferentiated iPS cells was originally hailed as the end of the controversial use of embryonic stem cells . However, iPSCs were found to be potentially tumorigenic, and, despite advances, were never approved for clinical stage research in the United States . Setbacks such as low replication rates and early senescence have also been encountered when making iPSCs, hindering their use as ESCs replacements . </P> <P> Additionally, it has been determined that the somatic expression of combined transcription factors can directly induce other defined somatic cell fates (transdifferentiation); researchers identified three neural - lineage - specific transcription factors that could directly convert mouse fibroblasts (skin cells) into fully functional neurons . This result challenges the terminal nature of cellular differentiation and the integrity of lineage commitment; and implies that with the proper tools, all cells are totipotent and may form all kinds of tissue . </P>

Which type of cell is most likely to remain totipotent