In PDAC, tumour-derived exosomes mediate the formation of a pre-metastatic microenvironment in the liver, which then facilitates colonisation by metastatic cancer cells.91 The exosomes, which contain high levels of macrophage migration inhibitory factor (MIF), are taken up by Kupffer cells, which are induced to express TGF-β. Here, TGFB1 is linked to neoplasm.