CXCR4 and posterior cortical atrophy: Moreover, metastatic PCa cells localized in the bone metastatic lesions express higher SDF1α/CXCR4 levels relative to the cells present in primary tumors and lymph node metastatic lesions [19–23], suggesting that the activation of the SDF1α/CXCR4 pathway may play a pivotal role in PCa bone metastases.