Actin - muscle specific

Author: Nat Pernick, M.D. (see Authors page)

Revised: 17 November 2015, last major update September 2013

Copyright: (c) 2003-2015,, Inc.

PubMed Search: Muscle specific actin[title]

Cite this page: Actin - muscle specific. website. Accessed July 18th, 2018.
Definition / general
  • Discovered in 1987 (Am J Pathol 1987;126:51); also called HHF35, MSA
  • Recognizes all alpha actins (skeletal, smooth, cardiac) and gamma smooth muscle actin; but not beta cytoplasmic or gamma cytoplasmic actin (the latter is also called non-muscle actin)
  • Recognizes actin expressed in all cells with muscle differentiation (cardiac, smooth and skeletal muscle), myoepithelial cells, myofibroblasts, pericytes and myogenic tumors (Am J Clin Pathol 1991;96:32)
Uses by pathologists
Microscopic (histologic) images

Images hosted on other servers:


Myofibroblastoma: breast (fig d)

Myofibroblastoma: lymph node

Prostate: normal smooth muscle stroma

Rhabdomyosarcoma: CNS, embryonal (left-fig 4; right-with anaplastic features)

Rhabdomyosarcoma: oral cavity

Images hosted on Flickr:

Glomus tumor

Positive staining - normal
  • Cardiac muscle, decidua, myoepithelial cells (although calponin and vimentin may be better, Braz Dent J 2007;18:192), myofibroblasts, pericytes, skeletal muscle, smooth muscle and vascular smooth muscle
Positive staining - disease
Negative staining