STK11 and breast cancer: Mutations in high penetrance genes such as breast cancer 1 (BRCA1), breast cancer 2 (BRCA2), phosphatase and tensin homolog (PTEN), tumor protein P53 (TP53), E-cadherin (CDH1) and serine/threonine kinase 11 (STK11) lead to an increased life-time risk of developing breast cancer up to 80% [32].