MK expression is significantly increased in many malignant tumors, including gastric cancer, pancreatic cancer, lung cancer, breast cancer, colorectal cancer, esophageal cancer, hepatocellular carcinoma and bladder cancer (Ren and Zhang, 2006; Krzystek-Korpacka et al., 2012; Zhao et al., 2012; Yao et al., 2014; Li et al., 2015; Yuan et al., 2015; Song et al., 2016; Vu Van et al., 2016). Here, MDK is linked to esophageal cancer.