 Pyrimidine dicarboxamides bind to this side pocket, which increases the selectivity.The role of MMP-13 is cleaving fibrillar collagen at neutral pH and higher mRNA levels of MMP-13 is detected in breast carcinoma and osteoarthritis joints.The pyrimidine dicarboxamide inhibitor example in the image does not interact with the catalytic zinc ion but rather binds to the S1’ side pocket.