sentences:  It is shown to be conserved in function across evolution as homologues of the protein are found both in vertebrates and invertebrates.The first members of the IAPs identified were from the baculovirus IAPs, Cp-IAP and Op-IAP, which bind to and inhibit caspases as a mechanism that contributes to its efficient infection and replication cycle in the host.Later, five more human IAPs that included XIAP, c-IAPl, C-IAP2, NAIP, and survivin were discovered.