MMP1 and disease of the tendon: In contrast, MMP1 was upregulated in human patellar tendinopathy [24] and increased expression of MMP1 was found in tendon ruptures [20,45,46] Additionally, upregulation of MMP2 and MMP9 was shown to be a feature of tendinopathy [20,43] and increased MMP9 activity was seen after exercise [47,48].