MMP1 and esophageal squamous cell carcinoma: To address this hypothesis, the human ESCC cell lines EC109 and EC9706 were stably transfected with MT3‐MMP‐expressing construct or empty vector as control, or conversely, infected with lentivirus encoding two different sequences of MT3‐MMP shRNA (designated as shMT3‐MMP‐1 or shMT3‐MMP‐2) or scrambled sequence as negative control.