Calpains are a large family of intracellular proteases whose precise and limited cleavage of specific proteins might be an integral regulatory aspect of signaling pathways. This intriguing mechanism for transducing biochemical and biophysical information from the external milieu seems to operate during cell motility. The two first described and ubiquitous isoforms, mu-calpain and M-calpain, have been implicated in enabling cell spreading by modifying adhesion sites and in promoting locomotion of adherent cells by facilitating rear-end detachment. Recent elucidation of the molecular structure of calpain opens the door for understanding how these pluripotential signal proteins are regulated to help govern migration. Armed with this knowledge, the precise roles of calpains in inflammation, wound repair and tumor progression can be ascertained and offer novel therapeutic targets.