Nature Med. doi:10.1038/nm.2011 (2009) Nature Med. doi:10.1038/nm.2020 (2009)

Cilia, the thin filaments that protrude from many mammalian cells, can both inhibit and exacerbate tumour formation in mice.

Cilia are essential for proper functioning of the hedgehog signalling pathway, which has been found to go haywire in various cancers. Jeremy Reiter of the University of California, San Francisco, and his colleagues deleted genes for cilia formation in two mouse models of skin cancer, each carrying a mutation in the hedgehog pathway. Tumours did not grow in mice with one mutation, but were accelerated in mice carrying the other.

Arturo Alvarez-Buylla, also at the University of California, San Francisco, and his colleagues found similar results modelling brain cancer in mice. In addition, they showed that some types of human brain cancer have cilia, whereas others do not, suggesting that cilia could aid in diagnosing cancer type.