The human SPARC gene is 26.5 kb long, and contains 10 exons and 9 introns and is located on chromosome 5q31-q33.

[5] Osteonectin is an acidic extracellular matrix glycoprotein that plays a vital role in bone mineralization, cell-matrix interactions, and collagen binding.

Osteonectin also increases the production and activity of matrix metalloproteinases, a function important to invading cancer cells within bone.

Additional functions of osteonectin beneficial to tumor cells include angiogenesis, proliferation and migration.

The phosphate is bound to the protein backbone through phosphorylated serine or threonine amino acid residues.