Figure 1

Cancer cells secrete exosomes into the tumor microenvironment in human MDA-MB-231 breast cancer orthotopic mouse models. The red fluorescent protein (RFP)-expressing MDA-MB-231-cells-produced exosomes which were labeled with a CD63-GFP fusion protein (MDA-MB-231-RFP/GFP-Exo). (A) MDA-MB-231-RFP/GFP-Exo cells secreted GFP exosomes in the primary tumor tissue. Blue arrows, MDA-MB-231-RFP/GFP-Exo cells; yellow arrows, secreted GFP exosomes. Scale bar = 100 μm. (B) MDA-MB-231-RFP/GFP-Exo cells secreted GFP exosomes at the lung colonization site. Yellow arrows, secreted GFP exosomes; blue arrows, lung metastatic MDA-MB-231-RFP/GFP-Exo cells. Scale bar = 20 μm. (C) Blue arrows, GFP-Exo incorporated in RFP stroma cells; yellow arrows, secreted GFP exosomes. Scale bar = 10 μm. (D) Blue arrows, GFP-Exo incorporated in RFP cancer-associated fibroblasts (CAFs); yellow arrows, secreted GFP exosomes. Scale bar = 10 μm [12].