All of us have lurking in our DNA a most remarkable gene. Its job is to protect us from cancer. This gene-known simply as p53-constantly scans our cells to ensure that when they grow and divide as part of the routine maintenance of our bodies, they do so without mishap. If a cell makes a mistake in copying its DNA during the process of division, p53 stops it in its tracks, sending in the repair team before allowing the cell to carry on dividing. If the mistake is irreparable and the rogue cell threatens to grow out of control (as happens in cancer), p53 commands the cell to commit suicide. Cancer cannot develop unless p53 itself is damaged or handicapped by some other fault in the system. Not surprisingly, p53 is the most studied single gene in history.
