Studies have highlighted the significance of zinc-containing enzymes called matrix metalloproteinases (MMPs), which can be activated by zinc.457,458 ZIP4, in particular, has been shown to regulate the expression of MMP2 and MMP9, influencing zinc concentration and promoting invasiveness and migration of hepatoma cells.397 Notably, ZIP4 expression is linked to post-liver transplantation outcomes in HCC patients, making it a potential treatment target and prognostic marker for liver transplantation in HCC cases. The gene discussed is MMP9; the disease is hepatocellular carcinoma.