Metaphase arrest and levels of polyploidy in lymphoma cell-lines after 10 Gy irradiation. p53 mutated Namalwa cells show a pronounced arrest in metaphase as seen by the high mitotic index on day 3 to day 5 (A) and near absence of anaphases and telophases (B) for a period of almost 10 days. Metaphase arrest is smaller and shorter in W1-L2-NS; (C) typical changes in the levels of polyploidy observed by DNA flow cytometry in Namalwa, W1-L2-NS and TK6 cells. (C) Reprinted from Ivanov et al., 2003. Both mitotic and endo-cycling are abrogated in wt p53 TK6 cells, which do not survive this irradiation insult.