An element is a pure substance that is made from a single type of atom. Elements are the building blocks for all the rest of the matter in the world. Examples of elements include iron, oxygen, hydrogen, gold, and helium.
Since the initial discovery that the adult brain contains stem cells that generate new neurons, an important question in neurobiology has been whether or not this adult neurogenesis is functionally important.
Specifically, the cancer stem cell hypothesis suggests that a distinct population of cells with stem cell properties is essential for the development and perpetuation of various human cancers, including pancreatic cancer (Al-Hajj et al., 2003; Hermann et al., 2007).