Less understood issues: p21(Cip1) in mitosis and its therapeutic potential

Oncogene. 2015 Apr 2;34(14):1758-67. doi: 10.1038/onc.2014.133. Epub 2014 May 26.


p21(Cip1) is a multifunctional protein and a key player in regulating different cellular processes. The transcription of p21 is regulated by p53-dependent and -independent pathways. The expression of p21 is increased in response to various cellular stresses to arrest the cell cycle and ensure genomic stability. p21 has been shown to be a tumor suppressor and an oncogene as well. The function of p21 in mitosis has been proposed but not systematically studied. We have recently shown that p21 binds to and inhibits the activity of Cdk1/cyclin B1, and is important for a fine-tuned mitotic progression. Loss of p21 prolongs the duration of mitosis and results in severe mitotic defects like chromosome segregation and cytokinesis failures promoting consequently genomic instability. Moreover, p21 is dramatically stabilized in mitotic tumor cells upon treatment with mitotic agents like paclitaxel or mitotic kinase inhibitors. Increased p21 is mainly localized in the cytoplasm and associates with cell survival indicating a crucial role of p21 in susceptibility to mitotic agents in tumor cells. In this review we will briefly summarize the structure and general physiological functions as well as regulation of p21, discuss in detail its role in mitosis and its potential to serve as a therapeutic target.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • CDC2 Protein Kinase
  • Cell Cycle Checkpoints / genetics*
  • Cell Survival / genetics*
  • Chromosome Segregation / genetics
  • Cyclin B1 / antagonists & inhibitors
  • Cyclin-Dependent Kinase Inhibitor p21 / biosynthesis
  • Cyclin-Dependent Kinase Inhibitor p21 / genetics*
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism*
  • Cyclin-Dependent Kinases / antagonists & inhibitors
  • Cytokinesis / genetics
  • Genomic Instability / genetics
  • Humans
  • Microtubule-Associated Proteins / antagonists & inhibitors
  • Mitosis / genetics*
  • Paclitaxel / pharmacology
  • Phosphorylation
  • Tubulin Modulators / pharmacology
  • Tumor Suppressor Protein p53 / metabolism


  • CCNB1 protein, human
  • CDKN1A protein, human
  • Cyclin B1
  • Cyclin-Dependent Kinase Inhibitor p21
  • KIF23 protein, human
  • Microtubule-Associated Proteins
  • TP53 protein, human
  • Tubulin Modulators
  • Tumor Suppressor Protein p53
  • CDC2 Protein Kinase
  • CDK1 protein, human
  • Cyclin-Dependent Kinases
  • Paclitaxel