PTP4A1 and esophageal cancer: The titer of autoantibodies against MFGE8, NRAS, PTP4A1, RRAS2 was measured in serum of 80 esophagus cancer cases (ECs), 80 hepatocellular carcinoma cases (HCCs), 80 lung cancer cases (LCs), and 80 healthy controls by ELISA.