MDM4 and cancer: In wild-type p53 cancer cells, p53 is functionally inactivated through the deregulation of its negative regulators, such as murine double minute 2 (MDM2) and MDM4, which may inhibit the transcriptional activity of p53 by themselves or promote the MDM2-mediated degradation of p53 by forming a heterodimer [16,17,18]; therefore, the reactivation of the p53 pathway by targeting these negative regulators of p53 represents a rational approach to controlling the growth of meningioma cells with wild-type p53.