CAST and breast cancer: In breast cancer, high calpain-2 expression is associated with adverse breast cancer-specific survival of patients with basal-like phenotype or triple receptor negative tumours [6]; high calpain-1 expression is associated with relapse-free survival of HER2 positive patients treated with adjuvant chemotherapy followed by trastuzumab [7]; and low calpastatin expression is associated with the presence of lymphovascular invasion [8].