CD9 and pancreatic neoplasm: Strikingly, sandwich ELISA using anti-CD9/CD63 mAbs and SN-131 (alkaline phosphatase-labelled) that PANC-1 cells release displaying cargo MUC1 TRD recognized by SN-131 (Fig. 4e–g and Fig. S5, ESI†), implicating that exosomes secreted from pancreatic cancer cells could interact directly with immune cells expressing Siglecs.