PDPN and neoplasm: TAMs can also secrete pro-angiogenic factor vascular endothelial growth factor (VEGF), placental growth factor (PLGF), and Sema4D to promote angiogenesis, and express podoplanin (PDPN, lymphatic marker) to promote lymphangiogenesis in paracrine and autocrine pathways, leading to tumor vascular and lymphatic metastasis (18, 35).