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PTEN is a phosphatase that converts inositol triphosphate to inositol diphosphate, thereby reversing the signaling effects of PI3 kinase. Thus, PTEN serves as a tumor suppressor in the PI3 kinase pathway. Loss of PTEN expression may occur through inactivating mutation, gene deletion, promoter methylation, or some combination of these alterations. Immunohistochemistry is a sensitive and reliable approach for assessing PTEN expression in tumors. PTEN loss is common in a number of malignancies, including prostate cancers, endometrial cancers, gliomas, and occasional lung and breast cancers.

At the Knight Diagnostic Laboratories, immunostaining for PTEN has been carefully optimized and shown to correlate well with the presence of PTEN mutations detected by next-generation sequencing. It should be noted, however, that poorly fixed specimens may not yield interpretable staining results.


  1. Staining is performed on 3-5 micron sections of formalin-fixed, paraffin embedded tissue.
  2. A Ventana autostainer is used to perform the staining.


Specimen Requirements:

  • A paraffin block or
  • 2 unstained sections of tumor (3-5 microns)
  • Contact Client Services for shipping materials and procedures at 855- 535-1522.

A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES.  Please include detailed clinical information.

Test Performed (Days):

Mon - Fri

Turn Around Time:

5 calendar days or less

Shipment Sensitivity Requirements:

  • Keep specimen cool during transit, but do not ship on dry ice.
  • Please use the cold pack provided in the KDL shipping kit.
  • Ship the specimen overnight express, using the FedEx priority overnight label provided. 
  • Contact Client Services for shipping materials and procedures at 855-535-1522.


Additional Info:

The Knight Cancer Institute at Oregon Health & Science University is a pioneer in the field of precision cancer medicine. The institute's director, Brian Druker, M.D., helped prove it was possible to shut down just the cells that enable cancer to grow. This breakthrough has made once-fatal forms of the disease manageable and transformed how cancer is treated. The OHSU Knight Cancer Institute is the only National Cancer Institute-designated Cancer Center between Sacramento and Seattle – an honor earned only by the nation's top cancer centers. It is headquarters for one of the National Cancer Institute's largest research collaboratives, SWOG, in addition to offering the latest treatments and technologies as well as hundreds of research studies and clinical trials.

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