ERBB2 and breast cancer: When we stratified our BC cohort based on hormonal receptor and HER2 expression, overexpression of KANK1 protein was predictive of longer BCSS in the receptor-negative subgroups (p = 0.024, p = 0.038 and p = 0.014 for ER−, PR− and HER2− tumours, respectively; Fig. 3a–c).