In this monocentric retrospective cohort study, tissue microarrays from 153 patients with histologically confirmed breast cancer were analyzed by immunohistochemistry to assess the expression of cytoplasmic Dkk1, β-catenin, and E-cadherin, as well as nuclear cyclin D1, KLF-4, KLF-5, and ERβ isoforms, using the Remmele and Stegner immunoreactive score. Here, KLF5 is linked to breast cancer.