H2AX and central nervous system cancer: However, D54 cells with TIP-1 knockdown had around 29.5% to 35.8% γ-H2AX foci-positives compared to the vector control which had only around 20% γ-H2AX foci-positives at 24 hours post 5Gy IR We also observed a remarkable portion of the cells with TIP-1 knockdown were stained as γ-H2AX foci positive even without IR treatment (Figs. 4B), suggesting a potential role of TIP-1 in maintaining the genomic integrity within glioma cells.