An overview of the cell cycle arrest protein, p21(WAF1)

Oral Oncol. 2000 Jan;36(1):3-7. doi: 10.1016/s1368-8375(99)00049-4.


p21, also known as WAF1, Cip1, Sdi1, Mda 6 and Cap20 is a cell cycle protein that regulates and can arrest the cell cycle in G1 or S phase (either dependent or independent of p53). Its role may be pivotal in many cell processes including differentiation and apoptosis. This brief overview provides a summary of its presently known functions and indicates areas for further research, particularly in relation to oral malignant disease. Greater understanding of its role may lead to therapeutic advances in the management of malignant disease.

MeSH terms

  • Apoptosis / physiology
  • Cell Cycle / physiology*
  • Cell Differentiation / physiology
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins / physiology*
  • Humans
  • Neoplasm Proteins / physiology
  • Neoplasms / metabolism
  • Tumor Suppressor Protein p53 / physiology


  • CDKN1A protein, human
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • Neoplasm Proteins
  • Tumor Suppressor Protein p53