¹³⁷Cs gamma-ray irradiation inhibits the colony formation by tumor cell lines <i>in vitro</i>.

<p>After ^<b>137</b>Cs gamma-ray irradiation (0, 30, 50 and 100 Gy), HepG2, SW620 and SGC7901 cells separated from human erythrocytes were cultured for 14 d, and then the colony formation was detected by Giemsa staining. Representative Giemsa staining (scale bar: 100 μm) of HepG2, SW620 and SGC7901 cells 7 d after irradiation (A). Colony formation rate of tumor cells at 14 d after irradiation (B). Data are means ± SEM; <i>n</i> = 6 erythrocyte samples from 6 volunteers in each group. ^<b>aa</b><i>P</i><0.01 vs. Con (the dose of irradiation was 0 Gy).