HGF and cancer: The migration patterns of macrophages and T cells depend on collagen expression.[41, 42, 43, 44] Elastin also facilitates recruitment of mononuclear phagocytes and is crucial for macrophage migration.[45, 46] Cancer‐associated fibroblasts (CAFs) are activated by signaling molecules such as transforming growth factor‐beta, platelet‐derived growth factor, and hepatocyte growth factor secreted from cancer cells.