MMP9 and Myocardial fibrosis: EGCG reduces the expression of type I and type III collagen in the hearts of diabetic rats, downregulates TGF-β1 and its downstream signaling molecules JNK, phosphorylated JNK, and tissue inhibitor of metalloproteinase-1 (TIMP-1), and upregulates matrix metalloproteinase-9 (MMP-9), thereby improving DCM-related myocardial fibrosis (Gui et al., 2022).