STK11 and breast cancer: According to epidemiological and experimental data, estrogens alongside the mutations in BRCA1 and BRCA2, CHEK2, TP53, STK11 (LKB1), PIK3CA, PTEN, and other genes, are key etiological factors of breast cancer development (Yaşar et al., 2017; Verigos and Magklara, 2015).