FN1 and neoplasm: We further evaluated whether the FN1/SPP1-ITGAV pathway was essential for the fibrosis-enhanced seeding and outgrowth of tumor cells in vivo. Compared with control peptide GRGES, GRGDS treatment inhibited the seeding of Hepa1-6-GFP and 4T1-luc in fibrotic lungs, as evidenced by reduced levels of GFP and luciferase in the lungs (Figure 6A).