PEBP1 and nonpapillary renal cell carcinoma: Urinary RKIP did not allow ccRCC to be distinguished from patients with chronic kidney disease (Figure 6A) but our experiments demonstrated that RKIP may be released in urine samples both as a free monomer and a phosphorylated dimer (p-RKIP) and that the evaluation of the latter form may be useful to distinguish ccRCC from CKD patients (Figure 6D–6E).