Expression of p53 and p21 in untransformed cells that stop cycling after cleavage failure. (A) Binuclear cell arrested after cleavage failure expressing p53 (red), p21 (green), and DNA (blue). (B) Daughters of a binuclear cell fixed 15 h after first tetraploid mitosis showing p53 (red) and p21 (green). (C) Percentages of cells expressing only p53, only p21, or both. The first column shows binucleates that arrested in first interphase, the second column shows daughters of binucleates, and the third column shows same-preparation control cells. Fluorescence micrographs are shown. Bar, 50 µm.