Overexpression of p21-induced polyploidization of UT-7 cells. pcDNA3 expression plasmid containing full-length p21 cDNA was introduced into UT-7 cells by electroporation. pSV-β-gal vector was simultaneously transfected to monitor the transfection efficiencies. As a control, empty pcDNA3 vector was transfected in the same manner (Mock). The cells were harvested after 3 days of the culture. (A) The percentage of polyploid cells was determined as described in the legend to Fig 1. The mean ± SD (bar) of three independent experiments is shown. (B) Wright-Giemsa staining of Mock- and p21-transfected cells is shown in the left panel. The result of in situ detection of β-galactosidase activity is shown in the right panel. (Original magnification × 400 and × 250, respectively).