CDKN1A and esophageal squamous cell carcinoma: Together, these results indicate that MT3‐MMP negatively regulates proliferation and aggressiveness of ESCC cells by blocking progression of cell cycle from G1 to S and then G2/M phase (e.g., through the restriction point of cell cycle), likely in association with up‐regulation of the endogenous Cdk inhibitors p21Cip1 and p27Kip1.