CXCR4 and posterior cortical atrophy: To explore the novel role of the CXCL12/CXCR4 axis in PNI, we evaluated the representative immunohistochemical staining properties of CXCR4 and CXCL12 in the resected PCa specimens accompanied by PNI, where the staining of S100 served as a nerve tissue marker and CK19 served as a cancer cell marker (Fig. 2A).