Interestingly, although calpain-1 has been described to proteolyze E-cadherin in breast cancer cell lines (Annunziato et al., 2016; Rodríguez-Fernández, 2019), it is not involved in the physiological cleavage of E-cadherin during mammary gland involution after weaning. This evidence concerns the gene CAPN1 and breast cancer.