SMAD3 and posterior cortical atrophy: Exosomes from PCa cell lines contain TGFβ1, which stimulates the differentiation of fibroblasts to highly aggressive myofibroblasts [124,125], an important source of matrix-remodeling proteins within the tumor microenvironment, via the activation of TGFβ/SMAD3 signaling, and thereby support PCa angiogenesis [124,125].