Calpain inhibitor XII is a reversible and selective inhibitor of calpain I (μ-calpain, Ki = 19 nM), with lower affinities for calpain II (m-calpain, Ki = 120 nM) and cathepsin B (Ki = 750 nM). Calpain inhibitors, including this compound, have been used to study the role of calpains in diverse processes, including neutrophil chemotaxis, neuronal signaling, and cardiac response to injury.
