Studies on human breast neoplasias have shown a reduced expression of the oestrogen receptors and of tumour-suppressive proteins, such as maspin, WT-1, and p63, by the epithelial cells close to areas exhibiting a loss of myoepithelial cells, thereby contributing to the aggressiveness and invasiveness of the tumour [28, 30, 32]. Here, SERPINB5 is linked to neoplasm.