The C-X-C motif chemokine receptor 4 (CXCR4) chemokine, previously linked to tumour metastasis [128] was differentially expressed between tumour and surrounding non-tumour tissue in African American men and the CXCR4 pathway was the highest-ranked pathway showing differential expression pattern among tumour and non-tumour tissue in African American men [127,129]. The gene discussed is CXCR4; the disease is neoplasm.