Overview:

Actin is an abundant cytoskeletal protein that is found in virtually all eukaryotic cells. At least six isoforms of actin have been identified in mammals. Because it is one of the most highly-conserved proteins, it is an excellent loading control for protein analyses. Actin is the monomeric subunit of microfilaments, one of the three major components of the cytoskeleton, and of thin filaments, which are part of the contractile apparatus in muscle cells. Thus, actin participates in many important cellular functions, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape (1).

References:

1. Lessard, J L.: Two monoclonal antibodies to actin: one muscle selective and one generally reactive. Cell Motility and Cytoskeleton 1998 10:349-362.