It has been observed that 137Cs γ-ray IR at single acute doses (0, 2, 5, 10, and 20 Gy) renders 17–20% of U87MG and LN229 cells dead but gives rise to 60–80% of growth-arrested GBM cells with elevation of senescence markers, such as SA-β-Gal+ cells, H3K9me3+ cells, and p53-p21cip1 + cells. The gene discussed is TP53; the disease is glioblastoma.