Expression of matrix metalloprotease-2 (MMP-2) and the activator membrane type 1 (MT1-MMP) in canine mammary carcinomas.

An immunohistochemical approach was used to examine the expression of MMP-2 and the activator MT1-MMP in a series of 50 canine mammary carcinomas of different histotype and stage. MMP-2 and MT1-MMP were mainly expressed in the cytoplasm of carcinoma cells and in fibroblasts. Immunolabelling for both MMP-2 and MT1-MMP was also seen on the tumour cell membranes. This labelling pattern showed no significant association with either the histological sub-type or stage of the carcinomas. Therefore, although distinct patterns of expression of MMP-2 and MT-MMP1 were shown by these carcinomas, functional studies by means of zymography would be required to provide useful information on tumour behaviour.