PEBP1 and nonpapillary renal cell carcinoma: Overall, our data indicate that urinary evaluation of RKIP and p-RKIP may permit ccRCC to be distinguished from other urological malignancies and CKD, and provide an explanation of the pathophysiological significance of the disappearance of both the monomeric and the dimeric form of this protein in urine samples of ccRCC patients.