I am a super-hero.

Scientists have discovered a gene which causes cells to start aging, rather than splitting off into new cells. With this discovery, comes another: the aging process of cells reduces the chance of cancer.

Rats with the gene, aged normally. Rats without the gene (supressed by scientists) didn't have many of the negative aspects to aging. Unfortunately, the rats also developed cancer at a highly accelerated rate. To be sure, none of the rats lived longer than the average natural lifespan of an ordinary rat - they just lived in better health (unless the rat happened to become cancerous).

So, alas, we still have some more work on achieving Highlander status.

Don't die.