Pancreatic cancer, one of the most deadly forms of the disease, can be stopped in its tracks by targeting an "Achilles' heel" protein, say scientists.
Blocking the molecule, called Yes-associated protein (Yap), did not prevent the disease but halted its growth.
Researchers hope the experiments, conducted on laboratory cell lines and mice, will one day lead to an effective treatment.
"We believe this is the true Achilles' heel of pancreatic cancer, because knocking out Yap crushes this really aggressive cancer," said US study leader Dr Chunling Yi, from Georgetown University Medical Centre.
"This appears to be the critical switch that promotes cancer growth and progression."
Pancreatic cancer is often diagnosed late and has one of the worst cancer survival records.
Yap is over-active in pancreatic cancer and other cancers, including those affecting the lungs, liver and stomach.
The new study, reported in the journal Science Signalling, involved mice with pancreatic ductal adenocarcinoma (PDAC), which accounts for 95pc of human pancreatic cancers.
Like humans with the disease, the mice have mutations in two key genes, KRAS and p53.
It has proved very difficult to develop drugs that target either of these gene defects. But Dr Yi's team discovered links between Yap and both KRAS and p53.
KRAS activates Yap, and Yap shuts down p53 – an oncogene that offers protection from cancer when it is not faulty.