Fletcher, L., Yen, T. J. and Muschel, R. J. DNA Damage in HeLa Cells Induced Arrest at a Discrete Point in G₂ Phase as Defined by CENP-F Localization. Radiat. Res. 159, 604–611 (2003).

G₂ is defined as the time in the cell cycle after DNA synthesis is complete but before the initiation of mitosis. However, as the molecular events of the cell cycle are described, G₂ can be seen to be a sequence of events rather than a static phase. For example, CENP-F increases in amount in early G₂, after DNA synthesis is complete, but localizes to the nuclear rim and then to the kinetochores before mitosis commences. After DNA damage cells may arrest in G₂ through TP53-dependent and independent mechanisms, raising the question of the precise position of the arrest within G₂. HeLa cells lack functional TP53; this allowed us to examine the TP53-independent mechanism of G₂ arrest. Here we showed that the DNA damage-induced G₂ arrest in HeLa cells is positioned in early G₂, before redistribution of CENP-F to the nuclear envelope and kinetochores, and before chromosome condensation commences.