STC2 and esophageal squamous cell carcinoma: Under physiological conditions, STC2 is highly expressed in skeletal muscle, heart, testis and pancreas8, 10; while under pathological conditions, STC2 is upregulated in a plethora of human tumours, including hepatocellular carcinoma (HCC), cervical cancer, nasopharyngeal carcinoma, colorectal cancer, gastric cancer, esophageal squamous cell carcinoma, prostate cancer, renal cell carcinoma, etc.7, 8, 11, 12.