In many ways, the biggest problem with fighting cancer is containing it: you may kill the main tumor site, but there's a real chance that it'll spread and reemerge as a threat. At last, though, scientists have a better understanding of how that migration happens. British researchers have learned that cancer cells invoke an unusual survival mechanism when they start to float through the body. Proteins on the cell surface (integrins) switch from their usual role, adhesion, to internal signalling that has the rest of the cell protect itself against death. The cancer is steeling itself for the journey, in other words.