Costa-Silva et al. found that pancreatic ductal adenocarcinomas (PDAC)-derived exosomal MIF induced bone marrow-derived cell migration to the liver and macrophage ablation blocked the pro-metastatic effect of PDAC-derived exosomes in the liver (Costa-Silva et al., 2015). The gene discussed is MIF; the disease is pancreatic ductal adenocarcinoma.