SDC1 and neoplasm: Noteworthy, strong communication probabilities mostly occur between ligands including collagens (type I, IV, and VI) and fibronectin (FN1), with receptors including integrin αVβ8 (ITGAV and ITGB8), syndecan 1 and 4 (SDC1 and SDC4), and CD44. These ligands and receptors dominate the active signaling between fibroblasts and tumor cells (Fig. 4b).