1.   Both groups enabled their cells to defeat the telomere-shortening system by activating an enzyme called telomerase, which builds telomeres back up to their normal length.

2.   But it is possible that its overexpression impairs the ability of the insulin receptor to activate cellular enzymes.

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

4.   Research has shown they can activate an enzyme that promotes bone growth, and in rats they have been shown to increase bone formation.

5.   The protein activates enzymes inside cells after insulin hitches itself to the cell membrane.