Representative examples of immunohistochemical analysis of Fez1, Fhit, p53, p27 and bcl2 proteins in primary Bellini's duct carcinoma of the kidney. A, Normal renal parenchyma shows uniform, cytoplasmic positive staining for Fez1 (×400). B, Fez1 protein is absent in this CDC (Case 1; ×400). An adjacent dysplastic distal duct (red arrow) shows strong Fez1 immunoreacticity. C, CDC section showing diffuse cytoplasmic staining for Fhit protein (Case 2; ×400). D, CDC neoplastic glands display strong nuclear immunoreaction for p53 oncoprotein (Case 5; ×400). Case 9 shows p27 immunoreactivity in both nucleus and cytoplasm (E) and bcl2 cytoplasmic immunostaining, red arrow (F) (×400).