Cell Cycle-Dependent Expression of Phosphorylated Histone H2AX: Reduced Expression in Unirradiated but not X-Irradiated G1-Phase Cells

Abstract MacPhail, S. H., Banath, J. P., Yu, Y. T., Chu, E. and Olive, P. L. Cell Cycle-Dependent Expression of Phosphorylated Histone H2AX: Reduced Expression in Unirradiated but not X-Irradiated G1-Phase Cells. Radiat. Res. 159, 759–767 (2003). Exposure of cells to ionizing radiation causes phosphorylation of histone H2AX at sites flanking DNA double-strand breaks. Detection of phosphorylated H2AX (γH2AX) by antibody binding has been used as a method to identify double-strand breaks. Although generally performed by observing microscopic foci within cells, flow cytometry offers the advantage of measuring changes in γH2AX intensity in relation to cell cycle position. The importance of cell cycle position on the levels of endogenous and radiation-induced γH2AX was examined in cell lines that varied in DNA content, cell cycle distribution, and kinase activity. Bivariate analysis of γH2AX expression relative to DNA content and synchronization by centrifugal elutriation were used to measure cell cycle-specifi...