Thus CMFDA-labeled HCT116 human colon cancer cells (wild-type (WT) HCT116 (HCT116WT) cells, isogenic control HCT116 (HCT116+/+) cells, and HCT116p53R248W/+ cells harboring the dominant-negative mutant of p53, p53R248W (Fig. 2a–h), or MCF7 human breast cancer cells (Fig. 2i–n) were irradiated with different doses (0, 4, 8, and 16 Gy), mixed after 24 h with CMTMR-labeled isogenic cells (1:1 ratio), and cultured for the indicated times. This evidence concerns the gene TP53 and breast cancer.