title: The expression of p21/WAF-1 and cyclin B1 mediate mitotic delay in x-irradiated fibroblasts.
abstract: BACKGROUND
  To better understand the relationship between mitotic delay and the disruption of cyclin B1 and p21 in x-irradiated fibroblasts, studies were carried out to establish correlations between the downregulation of cyclin B1 by the cyclin kinase inhibitor (CKI) p21 and the induction of mitotic delay in the NIH3T3 fibroblast.
  
  
  METHODS
  Cell cycle kinetics were used to analyze mitotic delay in irradiated NIH3T3 cells and immunocytochemistry incorporated to assess the expression of cyclin B1 and p21, following 2 or 4 Gy x-irradiation.
  
  
  CONCLUSIONS
  Results indicate a dose dependent increase in mitotic delay accompanied by a downregulation of cyclin B1 and corresponding upregulation of the CKI p21 in exponentially growing cultures. Data indicates that the induction of radiation-induced division delay appears to be dependent on the p21 inhibition of cyclin B1 and, furthermore, p21 and cyclin B1 expression are highly dependent on cell density.
authors.affiliation: Department of Physics, East Carolina University, Greenville, NC 27858, USA. mjc0302@mail.ecu.edu
authors.forename: Mickael J
authors.initials: MJ
authors.lastname: Cariveau
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Kovacs
authors.forename: Ron R
authors.initials: RR
authors.lastname: Allison
authors.forename: Roberta M
authors.initials: RM
authors.lastname: Johnke
authors.forename: Gerhard W
authors.initials: GW
authors.lastname: Kalmus
authors.forename: Mark
authors.initials: M
authors.lastname: Evans
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000502:physiology / Q000528:radiation effects; D018797:Cell Cycle Proteins / Q000096:biosynthesis* / Q000528:radiation effects; D019926:Cyclin B / Q000096:biosynthesis* / Q000528:radiation effects; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D051379:Mice; D008938:Mitosis / Q000502:physiology / Q000528:radiation effects*; D041681:NIH 3T3 Cells; D014965:X-Rays
chemical_list: C534700:Ccnb1 protein, mouse; C493957:Cdkn1a protein, mouse; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21