Strong and specific fluorescence was detected in OSPC-ARK-1-derived tumor xenografts after12 hrs (mean MFI ± SE = 1178 ± 406), 24 hrs (mean MFI ± SE = 2592 ± 1303), and 48 hrs (mean MFI ± SE = 1808 ± 677) after i.v. injection with FITC-conjugated CPE peptide (Figure 4 and Table 2), while little labeling of tumor cells was observed after injecting equimolar concentrations of fluorescein, or fluorescein and unlabeled CPE peptide separately into mice with size-matched ovarian tumors or tumors not overexpressing claudin-3 and clauidn-4 receptors (data not shown). The gene discussed is CLDN3; the disease is ovarian neoplasm.