Calpains are a highly conserved family of intracellular, non-lysosomal, calcium-dependent cysteine proteases which are found in organisms ranging from mammals to drosophila. Currently, at least 12 different calpains have been identified in mammals with ubiquitous (m- and μ-calpains) and tissue-specific (p94calpain-3 and calpain-4 in skeletal muscle) expression patterns. The m-calpains, μ-calpains and calpastatin are the best-characterized members in the family. They are pivotal proteases participating in limited proteolysis of a number of structural proteins, regulatory proteins and the tumor-suppressing protein Rb. One of the best-documented functions for these enzymes is the regulation of integrin-mediated cell migration...