HeLa cell - the "immortal cell"

A HeLa cell (also Hela or hela cell) is a cell type in an immortal cell line used in scientific research. It is one of the oldest and most commonly used human cell lines.[1] The line was derived from cervical cancer cells taken from Henrietta Lacks, a patient who eventually died of her cancer on October 4, 1951. The cell line was found to be remarkably durable and prolific as illustrated by its contamination of many other cell lines used in research.[2][3]

http://en.wikipedia.org/wiki/HeLa