Cathepsin K

Author: Nat Pernick, M.D.

Revised: 3 May 2018, last major update July 2013

Copyright: (c) 2003-2018,, Inc.

PubMed Search: cathepsin k
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Cite this page: Pernick, N. Cathepsin K. website. Accessed January 22nd, 2019.
Definition / general
  • Lysosomal, papain-like cysteine protease with high matrix-degrading activity; expression is driven by microphthalmia transcription factor (MITF) in osteoclasts
  • Responsible for bone resorption and remodeling
  • Germline mutations cause sclerosing osteochondrodysplasia pycnodysostosis, a rare autosomal recessive skeletal dysplasia characterized by abnormal bone and tooth development
Uses by pathologists
  • Diagnosis of renal angiomyolipoma and other renal erivascular epithelioid cell tumors (Mod Pathol 2012;25:100)
Microscopic (histologic) images

Images hosted on other servers:

Bone: osteoclasts in osteoclastoma and normal

Intervertebral disc

Maxillary sinus: basaloid squamous cell carcinoma

Positive staining - normal
Positive staining - disease
Negative staining