SPP1 and neoplasm: Also, osteopontin, a 300 amino acid protein normally produced from bone and other tissues (epithelia, mucosae, kidney) and overexpressed in tumors, binds to the cell integrin αvβ3, activating NF-kB and MAPK pathways, with the generation of MMP-9, resulting in tumor cell growth, proliferation, survival (anti-apoptotic), and metastases [2,11,49].