SPP1 and gastric cancer: As the main components of ECM, SPARC (acid-secreted and cysteine-rich secreted protein), BGN (biglycan), FBN1 (fibrillin 1), SPP1 (secreted phosphoprotein 1), fibronectin (FN1), and collagen play important roles in cell proliferation, differentiation, migration, and metastasis in GC [28].