Science doi:10.1126/science.1163040 (2009) Nature Biotechnol. doi:10.1038/nbt.1526 (2009)

Recent studies of human tumours have suggested that solid cancers carry a host of different genetic mutations. Working out which of these set off the disease is tricky, but a team led by David Largaespada of the University of Minnesota in Minneapolis has found a way.

The group engineered mice that contain a jumping gene, or transposon, that can be switched on or off in specific tissues. When it is turned on, it hops around the genome, disabling other genes by inserting copies of itself into them.

Largaespada and his colleagues have used this approach to identify 77 genes potentially involved in human colorectal cancer and 19 that are strongly implicated in liver cancer, some of which were not previously known to be mutated in human tumours.