CXCR4 and nonpapillary renal cell carcinoma: Of note, overexpression of CXCR4 is also associated with poor survival and worse prognosis in ccRCC [21–24], and the antagonist of CXCR4 reversed the tumor-promoting microenvironment in renal cancer [25], indicating that CXCR4 may be a theranostic target for ccRCC.