SPARC, or secreted protein acidic and rich in cysteine, is a calcium-binding matricellular glycoprotein secreted by many types of cells. It has a normal role in wound repair, cell migration and cell-matrix interactions. Its overexpression is thought to have a role in tumor invasion and angiogenesis. A few studies indicate that SPARC overexpression improves the response to the anticancer drug nab-paclitaxel. The improved response is thought to be related to SPARC's role in accumulating albumin and albumin-targeted agents within tumor tissue.