Immunostaining (Fig. 5) revealed AE1/AE3 positivity in the renal carcinoma, colon carcinoma, and normal renal tubules; CK7 positivity in the renal carcinoma and normal renal tubules; CK20 positivity only in the colon carcinoma; and c-kit and colloidal iron positivity in the chromophobe renal cell carcinoma. This evidence concerns the gene KRT7 and colon carcinoma.