The flies with cancer had mutations in the tumor-suppressor gene brain tumor (brat), which stopped the gene from functioning correctly. Inactivation of the brat gene causes the Drosophila larval brain to overgrow. The majority of larvae do not make it to adulthood – only 15% of them turn into flies. Surviving flies have large brains made up of cancerous tissue, and they normally die young.

If cells from this cancerous tissue are transplanted into a healthy fly, they grow rapidly and spread – forming secondary tumors around the fly’s body. The researchers plan to use the information that they have gathered from this experiment to elucidate which of the genes upregulated in these cancer cells are responsible for the cells’ metastatic behaviour.