Stains
Nucleophosmin (NPM)


Topic Completed: 1 June 2005

Revised: 7 March 2019

Copyright: 2002-2015, PathologyOutlines.com, Inc.

PubMed Search: Nucleophosmin [title]

Nat Pernick, M.D.
Page views in 2018: 42
Page views in 2019 to date: 46
Table of Contents
Definition / general
Cite this page: Pernick N. Nucleophosmin (NPM). PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/stainsnucleophosmin.html. Accessed September 18th, 2019.
Definition / general
  • Also called B23, numatrin; gene at 5q35
  • Highly conserved non-ribosomal nucleolar phosphoprotein involved in assembling preribosomal particles into small and large ribosomal subunits
    • Binds with high affinity to ss nucleic acids, exhibits activity that destabilizes the RNA helix and is associated with the most mature nucleolar preribosomal ribonucleoproteins
  • May contribute active promoter to NPM-ALK
  • ALK promoter is normally silent in lymphoid cells

  • Hypothesis
    • IL-2 or T-cell mediated signals activate substrates; with NPM-ALK, get constitutive activation (note ALCL arises from activated T lymphocytes, which depend on IL-2 for growth and viability)
    • Fusion protein found in anaplastic large cell lymphoma (13-50%)
    • When present, can be used to differentiate from Hodgkin lymphoma
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