PIK3CA and glioblastoma: Our results support an independent and more relevant role for the former gene as the target of 1q32 amplification, since a higher frequency of MDM4 amplification in the absence of involvement of CNTN2 was observed in our patients; despite this, in our series, 7 other candidate genes were amplified together with MDM4. These included the PIK3C2B gene involved in the PI3K/AKT signaling pathway, which was also amplified and overexpressed in other series of GBM [20], and the SOX13 gene, which has been reported to be up-regulated in oligodendrogliomas [59].