Figure 2. Exposure of E1A + E1B cells to IR results in the formation of giant polyploid cells, which are characterized by high level of E1A protein expression. (A) Microphotographs of cells stained with hematoxylin and eosin. Images were acquired in transmitted light, magnification 10 × 40. (B) Frequency distribution of cells according to DNA content was calculated by DNA cytometry of Feulgen-stained samples. Analysis of E1A expression in non-irradiated and IR-exposed cells by western blot (C) and immunofluorescent staining (D).