Fig. 4.

GONs enhanced the number of DNA double-strand breaks and extent of cell cycle arrest. a Fluorescent images of γ-H2AX foci in A549 cells were captured with a fluorescence microscope 2 h after radiation; scale bar is 20 μm; the nuclei stained with Hochest33342 are blue; the γ-H2AX foci visualized by incubating with fluorescent antibodies are red. b The numbers of foci per cell were counted over at least 50 cells. c The relative percentage of cells distributed in G2/M phase of cell cycle progression. *p < 0.05 or **p < 0.01 represent statistically significant or extremely significant differences, respectively