As cancer progression markers, exosomes with specific integrins predict metastatic organotropism.59 Tumor-derived exosomes contain integrins that prepare organ-specific sites where metastatic niches are established.59 These exosomes are uptaken by targeted resident cells like fibroblasts, macrophages, epithelial, and endothelial cells where they activate Src signaling and pro-inflammatory S100 gene expression.59 In murine breast cancer models, specific integrins, transferred by exosomes, determine the target organs where metastatic niches are prepared. The gene discussed is SRC; the disease is cancer.