For example, Pseudomonas aeruginosa exotoxin A [132,133], diphtheria toxin fragment A [134], doxorubicin-loaded polysialic acid nanoparticles [135], 111In [136], TNF [137], and nanomaterials such as gold nanoparticles [138] bound to C-CPE induces cell death in CLDN4-expressing cancer cells. This evidence concerns the gene CLDN4 and cancer.