November 14, 2023

p53 is a type of protein called a tumour suppressor made by normal cells throughout the body. Abnormal production of p53 protein can also be seen in many different types of precancerous conditions and cancerous tumours.

After it is made, p53 is held in a part of the cell called the nucleus. Pathologists use a test called immunohistochemistry to see this protein inside cells. The results of this test are used with other information to make a diagnosis.

When examined by immunohistochemistry, p53 can show three different patterns of expression:

  1. Wild type – This is the normal pattern for this protein. In this pattern of expression, the protein can be seen in some but not all normal cells.
  2. Overexpression – This is an abnormal pattern. In this pattern, the protein can be seen in all the abnormal cells.
  3. No expression – This is an abnormal pattern. In this pattern, the protein is not seen in any of the abnormal cells. Some pathologists call this the “null” pattern.

Overexpression or no expression of p53 can be seen in both pre-cancerous conditions and cancers. The gene responsible for producing this protein (also called p53) is altered (mutated) in many kinds of human cancers. These mutations cause the protein to be either over-expressed or not expressed in cancer cells.

About this article

This article was written by doctors to help you read and understand your pathology report. Contact us if you have questions about this article or your pathology report. For a complete introduction to your pathology report, read this article.

Other helpful resources

Atlas of pathology
A+ A A-

Did you find this article helpful?