CLDN4 and ovarian cancer: Here, we modulated claudin-4 in different ovarian cancer cells (HGSOC cells, OVCAR3, which do express claudin-4; LGSOC cells, OVCAR8, which do not express claudin-4; and MOC cells, OVCA429, which do express claudin-4; ref. 1) in vitro and in vivo [Patient-derived xenograft (PDX)-Humanized Immune System (HIS) mice; patient-derived xenograft-human immune system mice] systems to study the function of claudin-4.