CDKN2A and central nervous system cancer: Additionally, other mutations that are frequently encountered in human gliomas, such as amplification of platelet-derived growth factor receptor alpha (PDGFRα), deletion of the cell cycle regulator gene CDKN2A, and amplification of the EGFR gene can be present in these animal tumors [168], the combination of TP53 and PDGFRα mutations being relatively frequent in pediatric high grade glioma [78, 111, 116].