It has been demonstrated that patients whose tumors exhibited positive levels of MRP2 expression showed worse prognosis than patients with MRP2-negative tumors in many different types of malignancy, including hepatocellular carcinoma, ovarian carcinoma, esophageal squamous cell carcinoma, renal cell carcinoma, nonsmall cell lung carcinoma and pancreatic ductal carcinoma [19–25]. Here, ABCC2 is linked to esophageal squamous cell carcinoma.