Cell 133, 994–1005 (2008)

Some primary tumours stimulate the spread of cancer by releasing a protein called osteopontin, studies in mice suggest.

Robert Weinberg of the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, and his colleagues implanted tissue from vigorously growing human breast tumours into mice. They then injected tumour cells that normally grow slowly. The fast-growing tumours spurred the enlargement of the 'responder' tumours via osteopontin, which has been previously linked to poor prognosis in several human cancers. Blocking osteopontin's action may yield useful cancer treatments.