EDN1 and lung cancer: On the other hand, various growth factors secreted by lung cancer cells, such as EGF-like domain multiple 6, bone morphogenetic protein-7 (BMP-7), transforming growth factor-beta (TGF-β), endothelin-1 (ET-1), fibroblast growth factors (FGFs), platelet-derived growth factors (PDGF), etc., can directly affect the composition of the tumor microenvironment (16–19).