title: G2-block after irradiation of cells with different p53 status.
abstract: BACKGROUND
  Although it is clear that functional p53 is not required for radiation-induced G2 block, certain experimental findings suggest a role for p53 in this context. For instance, as we also confirm here, the maximum accumulation in the G2 compartment after X-ray exposure occurs much later in p53 mutants than in wild types. It remains to be seen, however, whether this difference is due to a longer block in the G2 phase itself.
  
  
  METHODS
  We observed the movement of BrdU-labeled cells through G2 and M into G1. From an analysis of the fraction of labeled cells that entered the second posttreatment cell cycle, we were able to determine the absolute duration of the G2 and M phases in unirradiated and irradiated cells.
  
  
  RESULTS
  Our experiments with four cell lines, two melanomas and two squamous carcinomas, showed that the radiation-induced delay of transition through the G2 and M phases did not correlate with p53 status.
  
  
  CONCLUSIONS
  We conclude that looking at the accumulation of cells in the G2 compartment alone is misleading when differences in the G2 block are investigated and that the G2 block itself is indeed independent of functional p53.
authors.affiliation: Department of Radiology, Toxicology and Civil Protection, Faculty of Health and Social Studies, University of South Bohemia in České Budějovice, Emy Destinové 46, 37005, České Budějovice, Czech Republic, zoelzer@zsf.jcu.cz.
authors.forename: Friedo
authors.initials: F
authors.lastname: Zölzer
authors.forename: Ganesh
authors.initials: G
authors.lastname: Jagetia
authors.forename: Christian
authors.initials: C
authors.lastname: Streffer
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D059565:G2 Phase Cell Cycle Checkpoints / Q000528:radiation effects*; D006801:Humans; D009374:Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology* / Q000532:radiotherapy; D011829:Radiation Dosage; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53