SapC-DOPS nanovesicles are a stable protein-lipid mixture assembled from saposin C (SapC) and dioleylphosphatidylserine (DOPS). It shows selective tumor-targeting activity in multiple animal tumor models and specific induction of apoptosis in various cancer cell lines. The preferential targeting is due to higher levels of exposed phosphatidylserine on the outer cell membrane of cancer cells. Importantly, induction of apoptosis by SapC-DOPS was shown to occur through intracellular ceramide elevation. Ceramide is known to be a tumor suppressor molecule capable of acting synergistically with Bax and regulating mitochondrial-mediated apoptosis. Effectors that mediate SapC-DOPS-induced apoptosis downstream of ceramide are currently unknown. Therefore, we hypothesized that mitochondria could play a major role during SapC-DOPS induced apoptotic cancer cell death. Cell death following SapC-DOPS treatment was assessed by several indices such as: G6PD release assay to estimate necrosis, DAPI staining and cell cycle analysis to estimate apoptosis and DNA fragmentation, JC-1 assay to estimate mitochondrial membrane potential (ΔΨM) and caspase-3 activation by Western blotting. SapC-DOPS treatment induced significant apoptosis as denoted by the appearance of a subG1 peak, loss of ΔΨM, mitochondrial release of Smac, Cyto c and AIF, as well as mitochondrial Bax translocation and oligomerization. ShRNA-mediated Smac knockdown and Bax inhibition with V5 peptide led to retention of ΔΨM and abrogation of apoptosis with decreased caspase-3 activation. Our results indicate that Smac and Bax play major roles in SapC-DOPS-induced mitochondria-mediated apoptotic pathway in human neuroblastoma cells