Fig. 6. Cycle arrest of GC-2spd cells induced by silica nanoparticles (A) control group, (B) 6.25 μg mL^–1 SiNPs group, (C) 12.5 μg mL^–1 SiNPs group, (D) 25 μg mL^–1 SiNPs group, (E) 50 μg mL^–1 SiNPs group, the cycle of GC-2spd cells treated with various concentrations of SiNPs for 24 h was measured by flow cytometry. The red, green, and yellow areas represent the G0/G1, S, and G2/M phases, respectively. (F) The proportions of G0/G1, S, and G2/M phase cells after exposure to silica nanoparticles (Mean ± S.E.) * indicates significant difference compared to control group (p < 0.05).