Furthermore, inhibition of HMD-2 with nutlin-3 partially eliminated the effects of TIP-1 expression on the p53 polyubiquitination and protein accumulation in the irradiated D54 cells (Fig. 6C), indicating that HDM-2 is involved in the TIP-1 regulated p53 inhibition in glioma cells. Here, MDM2 is linked to central nervous system cancer.