TGFB1 and neoplasm: In pancreatic cancer, Kupffer cells begin to secrete more TGF‐β, connective tissue growth factor, eosinophil‐derived neurotoxin, insulin‐like growth factor, and PDGF after taking up the exosomes from the PDAC, which enhances the production of fibronectin and creates a fibrotic microenvironment before tumor metastasis.[23] Macrophages treated with PDAC exosomes can also stimulate the secretion of PGE2, VEGF, monocyte chemo‐attractant protein (MCP)‐1, IL‐6, IL‐1β, MMP‐9, and TNF‐α.