CXCR4 and renal cell carcinoma: Many molecular pathogenic targets such as HIF, VEGF, carbonic anhydrase IX (CaIX), phosphatase and tensin homolog (PTEN), C-reactive protein (CRP), Erythropoietin (EPO), E-cadherin, C-X-C chemokine receptor type 4 (CXCR4), CD44, PAX8 and PAX2, Ki67, p21, p53, and other potential RCC biomarkers have been investigated.