We reasoned that claudin-4’s reduction of genomic instability and slowing of mitosis may interfere with olaparib’s effects on OVCAR8, OVCA429, and OVCAR3 cells, which, despite classification discrepancies (OVCAR8 and OVCA429), are recognized as ovarian cancer cell lines (43, 88–98). This evidence concerns the gene CLDN4 and ovarian carcinoma.