Osteopontin/OPN is a secretory glycophosphoprotein belonging to the SIBLING family. It contains RGD sequences and phosphorylation sites and can bind to integrins αvβ3, α4β1 and CD44 receptors. Osteopontin/OPN regulates cell adhesion and migration through receptor-mediated regulation, activates MAPK/ERK and PI3K-AKT to promote tumor invasion, and upregulates TIMP-1/2 to inhibit MMPs and protect cartilage. Osteopontin/OPN can be used in the study of osteoarthritis, liver cancer, etc[1][2][3].
