11.   This neomucisa contains all normal intestinal cell lineages and persists for the life of the animal.

12.   But they also kill other normal cells.

13.   One has been shown to have a direct effect on killing cancer cells while leaving normal cells unharmed.

14.   And because most normal cells in the body do not produce telomerase, such a drug would have little effect on healthy cells.

15.   And normal cells, he said, do not reshuffle their genes and so do not develop drug resistance.

16.   And the most sensitive cells, the normal cells that are most sensitive to chemotherapy, are the cells in the bone marrow.

17.   Another way that the body shows its age is that normal cells stop dividing.

18.   As a result, normal cells are doomed to a limited number of replications before they begin to age.

19.   At every turn, they can search for potential drugs that can block the newly discovered pathways that fling a normal cell down a cycle culminating in malignancy.

20.   A key advantage of angiogenesis-blocking drugs is their much lower toxicity than conventional cancer drugs that attack tumor cells but also unavoidably kill normal cells.