The p53 tumor suppressor network is frequently disrupted in GBM, and the deregulation of p53 antagonists, such as MDM2 and MDM4 (also known as HDMX and MDMX), is a primary contributor to p53 inactivation in this context.24 The MDM2 proteins are dysregulated in many human cancers, and they exert their oncogenic activity predominantly by inhibiting the activity of p53. The gene discussed is MDM4; the disease is cancer.