“…Although caspase-2 shares some substrate specificity with the executioner caspases [19], in many respects, it is also considered as an initiator caspase, and activate downstream molecules of caspase-3 and caspase-6 [20]. For instance, caspase-2 gene has been identified from marine invertebrates Pacific oyster Crassostrea gigas and sea cucumber Apostichopus japonicus after pathogens or LPS infection [21,22], and their roles in immune defense are well indicated.…”