CXCR4 and cancer: We further elaborated the role of CXCL12 interaction with its cognate receptor CXCR4 again using public available data and found that i) patients with aggressive cancers reflected by Gleason Score have higher CXCR4 expression levels, ii) the histological subtype of PCa does not influence CXCL12 or CXCR4 expression and iii) CXCR4 positively correlates with AR activity reflected by prostate specific antigen (PSA) expression (Fig. S3).