Several groups have demonstrated the importance of the chemokine CXCL12 [also known as stromal cell-derived factor 1 (SDF-1)] and its receptor CXCR4 in PCa cell proliferation in vivo (Zhang et al. 2008b; Sun et al. 2003) and in vitro (Taichman et al. 2002; Hirbe et al. 2010). Here, CXCR4 is linked to posterior cortical atrophy.