CXCL12 and posterior cortical atrophy: PCa cells express C-X-C chemokine receptor type 4 (CXCR4), which causes their homing to BM by C-X-C motif chemokine 12 (CXCL12)/CXCR4 signaling to compete with hematopoietic stem cells; further involvement by activation of the phosphatidylinositol 3-kinase (PI3K) and protein kinase B (Akt) pathway and higher presence of regulatory T cells in BM metastatic PCa lead to higher levels of CXCR4 to further drive spread [13].