CDKN2A and ependymoma: To create this model, first 204 patient samples were analyzed for copy number variations via SNP array and 83 of these samples by gene expression profiling, which identified two mutational events (deletion of the INK4A/ARF locus and amplification/overexpression of the ephrin-B receptor EphB2) as putative supratentorial ependymoma tumor suppressor (INK4A/ARF locus) and oncogene (EphB2).