The radiation-induced S-phase checkpoint is independent of CDKN1A

C. Y. Guo, J. A. D'Anna, R. Li, J. M. Larner

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


We recently demonstrated that, in response to radiation, replication is down-regulated at the level of individual origins throughout S phase of the cell cycle. Since several in vitro studies demonstrate that CDKN1A (formerly known as p21) down-regulates replication by inhibiting PCNA, and since CDKN1A can retard progression of cells through S phase in vivo, the question arises whether CDKN1A is involved in the S-phase damage-sensing pathway. In the present study we analyzed the effect of ionizing radiation on CDKN1A(+/+) and CDKN1A(-/-) cells derived from the HCT 116 cell line. Neither progression of cells through S phase nor survival after exposure to ionizing radiation is influenced by CDKN1A status in either synchronous or asynchronous cells. These results establish that CDKN1A is not necessary for the acute S-phase damage-sensing pathway that functions to prevent firing of replication origins during S phase.

Original languageEnglish (US)
Pages (from-to)125-132
Number of pages8
JournalRadiation Research
Issue number2
StatePublished - Feb 1999
Externally publishedYes

ASJC Scopus subject areas

  • Radiation
  • Biophysics
  • Radiology Nuclear Medicine and imaging


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