CXCR4 and prostate cancer: To examine the role of CXCR4 in response to either docetaxel treatment in the presence of activated macrophages, we knocked down CXCR4 expression in prostate cancer cells including PC-3 and C4-2, with two distinct pairs of short hairpin RNA targeting two different loci in the third exon of human CXCR4, which is shared across five isoforms from the PubMed gene database.