Selective binding of the CSNRDARRC peptide to rat bladder tumors upon instillation into the bladder. Selective binding of the CSNRDARRC peptide to rat bladder tumors upon instillation into the bladder. A 50 μmol/L solution of fluorescein-labeled CSNRDARRC peptide was introduced into the bladder of tumor-bearing (A-D) or normal (E and F) rats and incubated for 30 min with changing body position every 10 min. After incubation, the bladder was instilled with PBS buffer to wash out unbound peptides, removed, and fixed. The CSNRDARRC peptide localization in malignant epithelium (B). Costaining for cytokeratin 18 and the merge (C and D). Note that the peptide mainly distributed at the malignant epithelium (arrows) with little binding to the normal epithelium (arrowheads). The peptide does not bind to the epithelium of normal bladder, which is outlined with cytokeratin 18 staining in (F). H&E staining (A and E). Magnification, ×200. G. Quantification of fluorescence intensity. The average intensities (integrated intensity per unit area) of fluorescence in tumor and normal tissues (n = 3) were calculated. **, P < 0.01, ANOVA test. Seung-Min Lee et al. Mol Cancer Res 2007;5:11-19 ©2007 by American Association for Cancer Research