Okadaic acid overrides the S-phase check point and accelerates progression of G2-phase to induce premature mitosis in HeLa cells

Exp Cell Res. 1996 Aug 25;227(1):165-9. doi: 10.1006/excr.1996.0262.


Okadaic acid has been shown to induce premature mitosis in HeLa cells belonging to both S-phase and G2-phase. The response is dependent on concentration and perhaps also on the differential susceptibility of cells to okadaic acid (OA). OA resembles caffeine in its ability to override the DNA-replication check point but differs in being capable of inducing premature mitosis in cells in G2-phase, thereby accelerating mitosis. Chromosomes from mitotic cells induced in G2-phase show a typical banding pattern similar to G-banding. From immunoblot experiments and survey of the relevant literature it has been argued that OA may modulate both a tyrosine kinase and a tyrosine phosphatase activity to override the S-phase checkpoint and accelerate the activation of MPF in cells in G2-phase, respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle / drug effects
  • Chromosomes, Human / physiology
  • Cyclin B*
  • Cyclin B1
  • Cyclins / analysis
  • Cycloheximide / pharmacology
  • Ethers, Cyclic / pharmacology*
  • G2 Phase / drug effects*
  • HeLa Cells
  • Humans
  • Mitosis / drug effects*
  • Okadaic Acid
  • Protein Synthesis Inhibitors / pharmacology
  • S Phase / drug effects*


  • CCNB1 protein, human
  • Cyclin B
  • Cyclin B1
  • Cyclins
  • Ethers, Cyclic
  • Protein Synthesis Inhibitors
  • Okadaic Acid
  • Cycloheximide