MMP9 and breast cancer: To screen the distributions of MMP‐9 in canine breast cancers, the surgically removed samples from 34 cases of pathologically diagnosed tubulopapillary carcinoma characterized by the formation of tubules and/or papillary projects and 18 cases of benign breast adenoma with well‐differentiated luminal epithelial or myoepithelial cells were collected and enrolled in this study.