FN1 and neoplasm: Based on the above background, this study proposes the following scientific hypotheses: metastatic CAFs promote invasion by secreting FN1 to activate the integrin-PI3K/AKT signaling axis in tumor cells; simultaneously, FN1 shapes an immunosuppressive microenvironment by recruiting M2 macrophages and Tregs, indirectly accelerating the metastatic process.