CXCR4 and posterior cortical atrophy: A previous study suggested a role for CXCL12 in the creation of a pre-metastatic niche in bone through the upregulation of CXCL12 expression in MSCs by PCa exosome-derived pyruvate kinase M2 (PKM2) and demonstrated a CXCR4-dependent increase in metastatic seeding and growth of PC3 cells in mice treated with PCa exosomes (83).