CLDN4 and ovarian cancer: Interestingly, we discovered that the PFS (progression-free survival) was significantly reduced in ovarian cancer patients when the expression level of the related genes was high (p < 0.05), as were the related hub genes, including ITGB2 (HR = 1.24, p = 0.0027), VEGFA (HR = 1.38, p = 1.8 × 10−5), CLDN4 (HR = 1.22, p = 0.0047), OCLN (HR = 1.38, p = 9.1 × 10−6), and SPP1 (HR = 1.38, p = 7.7 ×10−7).