Osteopontin is a versatile cytokine that belongs to the family of small integrin-binding ligand N-linked glycoprotein (SIBLING) secreted phosphoproteins, originally described in bone—hence the name—but later found to be expressed in several organs, especially in response to tissue damage, and with important roles in tissue repair and regeneration, regulation of the inflammatory response, and tumor progression and metastasis [29,30,31]. Here, SPP1 is linked to neoplasm.