MDM2 and anaplastic meningioma: Inactivation of the G1/S-phase cell cycle checkpoint was reported to be an important aberration in anaplastic meningiomas (Boström et al. 2001), and it was suggested that deregulations of p14-MDM2-p53 pathway may contribute to the malignant progression of those tumors (Amatya et al. 2004).