Via EurekAlert, more evidence for cancers being caused by errant stem cells: "Researchers elsewhere already have implicated stem cells in the development of leukemia, and Steindler's lab previously discovered stem-like cells in brain cancer. Others have identified these same cells in some breast cancers. ... The cancer stem cell theory holds that a small subpopulation of rogue stem cells exists within a tumor and has the ability to sustain itself. As these abnormal cells divide, they may generate the bulk of a malignant tumor, then help to spur on its growth. ... The next step, which is ongoing, is isolating and growing tumors from these cells in animals and then finding ways to interfere with that growth based on their stem cell biology."