Figure 1.

HNSCC cells with mutp53 exhibit resistance to radiation-induced senescence. (a) Clonogenic assay showing the differences in radiosensitivity among isogenic pair HN30 (wtp53) and HN31 (heterozygous mutant p53 alleles A161S and C176F), their p53 knockdown counterparts (shp53) and PCI-13 cells harboring either null or wtTP53 or, A161S or C176F TP53 mutations. (b) SA-β-gal staining of the cell lines described in a was performed 4 days after the cells were exposed to 4-Gy ionizing radiation. (c) Quantitation of SA-β-gal-positive senescent cells (those staining blue) from four randomly selected fields