A protein has been found that suppresses colorectal cancer in both mice and human cell cultures. Colorectal cancers are the second leading cause of cancer deaths, with half of all people developing colon tumours by the age of 70. Immunologist Josef Penninger of the Ontario Cancer Institute says that, contrary to what was expected, mice genetically engineered without the protein developed invasive colorectal cancer and died. “Every prediction about this protein had been that it actually caused cancer,” says Penninger. The next step is to study the exact workings of this protein in colon cancer, which Penninger says could lead to future drug therapies, replicating or stimulating the protein to stop tumour growth. Researchers will also investigate whether some people have a predisposition to colorectal cancer.