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Updated: Sep 28, 2026

Cell Cycle-specific Measurement of γH2AX and Apoptosis After Genotoxic Stress by Flow Cytometry
Published on: September 1, 2019
Influence of environmental pH on G2-phase arrest caused by ionizing radiation
Heon Joo Park1, Sang Hwa Lee, HyunSook Chung
1Department of Microbiology, Inha University, College of Medicine, Inchon, Korea.
Abstract:
We investigated the effects of an acidic environment on the G2/M-phase arrest, apoptosis, clonogenic death, and changes in cyclin B1-CDC2 kinase activity caused by a 4-Gy irradiation in RKO.C human colorectal cancer cells in vitro. The time to reach peak G2/M-phase arrest after irradiation was delayed in pH 6.6 medium compared to that in pH 7.5 medium. Furthermore, the radiation-induced G2/M-phase arrest decayed more slowly in pH 6.6 medium than in pH 7.5 medium. Finally, there was less radiation-induced apoptosis and clonogenic cell death in pH 6.6 medium than in pH 7.5 medium. It appeared that the prolongation of G2-phase arrest after irradiation in the acidic environment allowed for greater repair of radiation-induced DNA damage, thereby decreasing the radiation-induced cell death. The prolongation of G2-phase arrest after irradiation in the acidic pH environment appeared to be related at least in part to a prolongation of the phosphorylation of CDC2, which inhibited cyclin B1-CDC2 kinase activity.
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