A recent study suggested a novel role for claudin-6 as a receptor for CPE by showing that the CPE sensitivity of an ovarian cancer cell line that does not express claudin-3 and claudin-4 is decreased in response to claudin-6 knockdown, while ovarian cell lines resistant to the effects of CPE can be made sensitive through claudin-6 overexpression [115]. The gene discussed is CLDN4; the disease is ovarian cancer.