MUC1 and cancer: Although the underlying molecular mechanism determining differences in the body circulation and organotropism between NS-MUC1-5T and NS-MUC1-5ST remains unclear, we conceive that exosomes carrying MUC1 TRD-STs disseminated from the primary pancreatic cancer sites could contribute to organotropic cancer metastasis through the interaction with Siglecs of tissue-resident immune cells at the preferential pre-metastatic sites.