Newswise — Normally, when a cell becomes damaged or doesn’t divide properly, the body’s natural recycling process breaks it down and it dies. Sometimes, though, the damage is to the genes that control a cell, and the result is out-of-control division. When this happens, a cancer cell is born.
http://www.newswise.com/articles/learning-about-cancer-by-studying-stem-cells?ret=/articles/list&category=medicine&page=1&search%5Bstatus%5D=3&search%5Bsort%5D=date+desc&search%5Bsection%5D=10&search%5Bhas_multimedia%5D=
Learning About Cancer by Studying Stem Cells