Taking advantage of the claudin-binding activity of full-length cCPE, Neesse et al. fused this fragment to glutathione S-transferase (cCPE.GST, 41 kDa) and fluorophore Cy5.5 to visualize claudin-4 overexpression in tumor xenograft and genetically engineered mouse models of pancreatic cancer by near-infrared imaging (14). This evidence concerns the gene CLDN4 and familial pancreatic carcinoma.