SPARC and breast cancer: The different distribution profiles of the apoptotic cases in these treatment groups may be attributed to the tumor penetration ability of PTX emulsion and PTX nanoparticle: PTX emulsion facilitates intracellular delivery of PTX into breast cancer cells via LDLR-mediated endocytosis and PTX nanoparticle exploits the natural property of albumin to reversibly bind to PTX, transports it across the endothelial cell via glycoprotein 60-mediated transcytosis, and accumulates it in tumors by albumin binding to SPARC (secreted protein, acidic and rich in cysteine) [12, 35–37].