KCNN4 and breast carcinoma: To define the role of KCa3.1 in therapy resistance of breast cancer, the response of MMTV-PyMT breast cancer cells to chemo- and radiotherapy was analyzed in vitro and in an orthotopic and syngeneic mouse model in dependence on wildtype (WT) versus knockout (KO) genotype or pharmacological blockade of KCa3.1.