MMP9 and hepatocellular carcinoma: A 4-EMT genes signature (E-cadherin (CDH1), inhibitor of DNA binding 2 (ID2), matrix metalloproteinase 9 (MMP9), and transcription factor 3 (TCF3)) was used to predict clinical outcome in a cohort of 128 hepatocellular carcinoma patients and then validated in an independent cohort of 231 patients with hepatocellular carcinoma from three different institutions [51].