CDKN2A and oligoastrocytoma: Dai and colleagues demonstrated that oligodenrogliomas and oligoastrocytomas could be produced in INK4a/ARF -/- mice by forcing glial precursor cells to overexpress PDGF, using the RCAS system [45], which involves delivery of oncogene-encoding viral vectors to cells that have been engineered to express receptor for RCAS virus.