By contrast, in luminal A/B and HER2-positive breast cancer cases, there were no significant differences in overall and recurrence-free survival between "CLDN4-high/LXRβ-high" and "CLDN4-low and/or LXRβ-low" groups, possibly due to the influence of valid endocrine therapy and anti-HER2 drug, both of which could mask effects of the CLDN4–LXRβ signaling in breast cancer. This evidence concerns the gene CLDN4 and breast cancer.