CASP9 and neoplasm: Apoptosis is orchestrated by Caspases, a family of cysteine proteases that cleave their substrates on the carboxy-terminal side of specific aspartic acid residues.24 Previous study has shown that introduction of PDCD4 induced the cleavage of CASP9, 3, 6, 7 and PARP in tumor cells.25 To further validate that miR-23a/b can suppress gastric cell apoptosis by regulating PDCD4, we investigated the effects of miR-23a/b and PDCD4 on several well-characterized biochemical markers for apoptosis, including cleaved-CASP9, 3, 6, 7 and PARP.