ANGPT2 and neoplasm: Tumor hypoxia microenvironment stimulates tumor cells, tumor stroma cells, and tumor-infiltrating inflammatory cells to express a series of lymphangiogenic factors, including the well-known VEGF family, especially VEGF-A/C/D (74), and other mediators such as PDGF-BB (75), IGF1/2 (76), FGF2 (77–79), HGF (80, 81), angiopoietin-2 (82), sphingosine-1-phosphate (83), adrenomedullin (84), and IL-7 (85, 86).