Calpain activation is upstream of caspases in radiation-induced apoptosis.
Waterhouse NJ, Finucane DM, Green DR, Elce JS, Kumar S, Alnemri ES, Litwack G, Khanna K, Lavin MF, Watters DJ. Calpain activation is upstream of caspases in radiation-induced apoptosis. Cell Death Differ. 1998 Dec; 5(12):1051-61.