FN1 and neoplasm: Examination of the interactions between fibroblast-like cells and tumor cells (Fig. 7) shows that strong communications occur between ligands including collagens (type I, IV, and VI) and fibronectin (FN1), with receptors (SDC1, SDC4, and CD44), which indicates that the tumor-associated fibroblasts potentially contribute to a unique ECM and mediate the activities of tumor cells.