51.   It has no effect on normal cells.

52.   It now plans to study whether activating the enzyme can extend the lifespan of normal cells.

53.   It starts in nerve cells near the kidney, normal cells doing their job to keep a small body functioning.

54.   Normal adult cells cannot grow and divide indefinitely in a test tube.

55.   Normal human cells have been dried out and revived eight days later using a trick evolved by a bacterium that can survive for centuries without water.

56.   Not only are these cells malfunctioning, but cancer cells suppress the immune system, so normal cells are malfunctioning.

57.   Normal cells have an intricate circuitry of interacting genes and proteins that control their proliferation.

58.   Normal human cells, however, do not contain the enzyme.

59.   Once Rituxan has cleared the body the stem cells can mature into normal differentiated cells like B cells.

60.   Oncogenes dictate the production of proteins that stimulate normal cell growth.