It suggest that c FLIP downregulation may play a crucial role in mediating apoptosis induced by API 1 or by the mixture of API 1 and TRAIL. Considering that TRAIL is being examined as a cancer therapeutic agent in clinical studies, the further study of the possible application of the API 1 PF299804 and TRAIL mixture in cancer treatment is justified. Recently, targeting the Akt protein kinase or the TRAIL mediated apoptotic pathway is emerged as attractive techniques for cancer chemoprevention. Certainly, a phase 0 chemo-prevention test on an orally effective Akt chemical has been successfully conducted recently. Ergo, the potential of the API 1 alone or in combination with TRAIL in cancer chemoprevention needs investigation also. We noted that, among the tested cancer cell lines, Calu 1 was the only cell line that displayed resistance to API 1 alone or the mix of TRAIL and API 1. Thus knowledge of the mechanisms through which API 1 induces apoptosis, including modulation of TRAIL induced apoptosis, will be beneficial for guiding effective application of API 1 in potential treatment of cancer in the center. Gene expression It is well known that cells may die of apoptosis primarily through the extrinsic death receptor induced pathway and/or the implicit mitochondria mediated pathway. Cross-talk between these two pathways is mediated by the truncated proapoptotic protein Bid. The activation of caspase 8 is the key step in the death receptor mediated apoptosis, whereas caspase 9 activation is the key even yet in the mitochondria mediated apoptotic pathway. Activated caspase 8 can also induce caspase 9 activation through Bid mediated activation of the mitochondria mediated apoptotic pathway. In this study, we found that purchase AG-1478 API 1 activated both caspase 8 and caspase 9, suggesting that API 1 either activates the death receptor mediated apoptotic pathway or mitochondriamediated apoptotic pathways and both the death receptor, resulting in induction of apoptosis. DR5, dr4 and d FLIP are key components in the regulation of TRAIL induced apoptosis. Modulation of the quantities of these proteins generally in sensitization of cancer cells to TRAILinduced apoptosis. We discovered that API 1 lowered c FLIP levels without increasing DR4 or DR5 expression in the painful and sensitive cancer cell lines. Apparently, Calu 1 cells, which are relatively immune to API 1 or API 1 plus TRAIL, indicated the highest basal levels of c FLIP, which wasn’t lowered by API 1. Enforced expression of ectopic FLIPL or FLIPS didn’t confer resistance to API 1 alone, but certainly attenuated or abolished the aftereffect of API 1 on improving TRAIL induced apoptosis in both H157 and 22A cells. For that reason, d FLIP down-regulation may not be sufficient for API 1 to initiate apoptosis, suggesting that other mechanisms are needed for API 1 induced apoptosis.