AstraZeneca (nyse: AZN - news - people ) is in midstage trials with 180 melanoma patients for a drug that hits a related target called mitogen-activated protein kinase kinase.
It appears to block the action of a protein called Stat 1, which becomes activated within cells after a stressful event such as a heart attack or stroke, and plays a role in inducing cell death.
This second gene, activated whenever the gene for P16INK4A was active, produced a protein that was harmless in itself, but which could be made deadly by the presence of a particular drug.