KCNAB2 and nonpapillary renal cell carcinoma: While we did not evaluate the level of autoantibodies against KCNAB2 and GAPDH in sera of other types of cancer, referring to published results of screening autoantibodies based on proteome microarrays for a variety of tumors, autoantibodies against KCNAB2 and GAPDH seems to be specific in ccRCC.