Importantly, SMAD4, SMAD3, and other key components of the TGF-β/SMAD signaling pathway (i.e., TGFβr1, TGFβr2, and SMAD2) are found within exosomes isolated from tumor cell lines and from human plasma samples (Supplementary Figures 1 & 9). This evidence concerns the gene TGFB1 and neoplasm.