News-Medical.net reports on confirmation of "immortal DNA" in stem cells: "When a cell divides, its DNA is duplicated and each resulting daughter cell inherits one copy of the DNA. Over time, errors arising during the duplication process can lead to mutations and cause cancers. ... A stem cell can produce two different daughter cells when it divides in the body - another stem cell and a specialised cell that will contribute to the tissue. This is called 'asymmetric division' and helps stem cells regulate their numbers and retain their capacity to regenerate tissue throughout the life of an organism. According to the immortal DNA hypothesis, when a stem cell divides, only the specialised cell inherits the imperfect copied DNA. The stem cell retains the original 'immortal' DNA strand." There are many other sources of DNA damage that can affect a stem cell, possibly turning it into a cancer stem cell. The full paper for this research - which outlines thoughts on immortal DNA, stem cells and aging - is freely available at Cancer Research.