An in vitro study showed that Slug up-regulates both CXCL12 and CXCR4 and impacts on CXCL12/CXCR4 signaling downstream target gene, MMP9, leading to highly invasiveness of PCa [85], implying that up-regulation of autocrine CXCL12 is a critical mechanism underlying Slug-mediated migration and invasion of PCa. The gene discussed is MMP9; the disease is posterior cortical atrophy.