KLF4 and breast cancer: Additionally, GWAS-PW identified three regions showing high probability of shared associations between depression and ER + BC, including two regions near 6p22.2 (6p22.1, PPA_3 = 0.71; 6p22.3–22.2, PPA_3 = 0.89), and one region at 9q31.2 (PPA_3 = 0.52, harboring a previous-reported BC locus KLF4) (Fig. 2).