PPBP and renal cell carcinoma: To identify additional CXC chemokines associated with tumorigenesis, progression, and clinical outcome in RCC, we evaluated all the CXC cytokines that were differentially expressed in RCC tumors vs normal tissues (CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL7, CXCL9, CXCL10, CXCL11, CXCL12, CXCL13, and CXCL16).