TM4SF1 and neoplasm: In addition, a recent report shows that collagen I could enhance TM4SF1-discoidin domain receptor 1 (DDR1) interaction by inducing DDR1 aggregation and recruitment of TM4SF1, thus forming TEMs to activate intracellular signaling pathways, which implies that matrix protein may be crucial for TEMs formation and thereby promote tumor metastasis [11].