SPP1 and neoplasm: Furthermore, fibronectin 1 (FN1) and secreted phosphoprotein 1 (SPP1) secreted by the fibrotic lung-derived fibroblasts promoted the chemotaxis and the apoptosis resistance of tumor cells via FN1/SPP1-Integrin αv (ITGAV) signaling, thereby facilitating the seeding and outgrowth of tumor cells in the lung.