Moreover, about 80–90% of CRPC patients develop bone metastasis, since the PCa cells expressing the E-selectin ligand CD44, αvβ3 integrin, and CXCR4 bind to bone marrow endothelial cells, bone marrow stromal cells and mesenchymal stem cells to promote bone homing of PCa [33, 34]. The gene discussed is CXCR4; the disease is posterior cortical atrophy.