Pilocytic astrocytoma (PA) is the most common pediatric brain tumor, and there are few medical therapies available to those patients for whom surgery is not curative. However, it has been difficult to design targeted PA therapies because the cellular mechanisms that lead to the cancer are incompletely understood, and there is no animal model of the disease.

Recent work has suggested that activation of a particular cell signaling pathway may be required for PA formation, and mutations in one gene in that pathway, a kinase called BRAF, are found in more than half of all PA cases. In this paper, Peter Lichter and colleagues at the German Cancer Research Center, in Heidelberg, Germany investigated how BRAF protein contributes to PA formation. They found that expression of just part of the BRAF protein in mice was sufficient to induce the formation of brain tumors that closely resembled the human disease. They are hopeful that this new animal model helps define the molecular processes that lead to PA, and may be useful in the design and testing of new therapeutics.